hey i have a probleme with this visualforce page when i selsct the language switcher to frensh nothing change , can tell or give a solution for this :
<apex:page controller="SiTFormController2" title="Stay in touch" showHeader="false" sidebar="false">
    <apex:stylesheet value="{!URLFOR($Resource.AcuerdoCUR__SiT_styles)}"/>

    <apex:variable var="selectedLanguage" value="English" />

    <div id="stylized" class="myform">
        <apex:form>
            <apex:outputPanel id="Ok" rendered="{!isSend}">
                <h1>
                    <apex:outputText value="Thank you" rendered="{!selectedLanguage == 'English'}" />
                    <apex:outputText value="Merci beaucoup" rendered="{!selectedLanguage == 'French'}" />
                </h1>
                <p>
                    <apex:outputText value="Your information has been sent to {!Contact.Owner.Email}" rendered="{!selectedLanguage == 'English'}" />
                    <apex:outputText value="Vos informations ont été envoyées à {!Contact.Owner.Email}" rendered="{!selectedLanguage == 'French'}" />
                </p>
            </apex:outputPanel>

            <apex:outputPanel id="Form" rendered="{!NOT(isSend)}">
                <apex:commandLink value="English" action="{!setLanguageEnglish}" rendered="{!selectedLanguage != 'English'}">
                    <apex:param name="selectedLanguage" value="English" assignTo="{!selectedLanguage}" />
                </apex:commandLink>
                <apex:commandLink value="French" action="{!setLanguageFrench}" rendered="{!selectedLanguage != 'French'}">
                    <apex:param name="selectedLanguage" value="French" assignTo="{!selectedLanguage}" />
                </apex:commandLink>

                <h1>
                    <apex:outputText value="Please enter your updated contact information" rendered="{!selectedLanguage == 'English'}" />
                    <apex:outputText value="Veuillez entrer vos informations de contact mises à jour" rendered="{!selectedLanguage == 'French'}" />
                </h1>
                <p>
                    <apex:outputText value="Information entered in this section will be sent to: {!Contact.Owner.Email}" rendered="{!selectedLanguage == 'English'}" />
                    <apex:outputText value="Les informations saisies dans cette section seront envoyées à : {!Contact.Owner.Email}" rendered="{!selectedLanguage == 'French'}" />
                </p>

                <label>
                    <apex:outputText value="Salutation" rendered="{!selectedLanguage == 'English'}" />
                    <apex:outputText value="Salutation" rendered="{!selectedLanguage == 'French'}" />
                    <span class="small"></span>
                </label>
                <apex:selectList value="{!Contact.Salutation}" multiselect="false" size="1">
                    <apex:selectOption itemValue="" itemLabel="--None--" />
                    <apex:selectOption itemValue="Mr." itemLabel="Mr." />
                    <apex:selectOption itemValue="Ms." itemLabel="Ms." />
                    <apex:selectOption itemValue="Mrs." itemLabel="Mrs." />
                    <apex:selectOption itemValue="Dr." itemLabel="Dr." />
                    <apex:selectOption itemValue="Prof." itemLabel="Prof." />
                </apex:selectList>

                <label>
                    <apex:outputText value="Firstname" rendered="{!selectedLanguage == 'English'}" />
                    <apex:outputText value="Prénom" rendered="{!selectedLanguage == 'French'}" />
                    <span class="small"></span>
                </label>
                <apex:inputText value="{!Contact.FirstName}" />

                <label>
                    <apex:outputText value="Name" rendered="{!selectedLanguage == 'English'}" />
                    <apex:outputText value="Nom" rendered="{!selectedLanguage == 'French'}" />
                    <span class="small"></span>
                </label>
                <apex:inputText value="{!Contact.LastName}" />

                <label>
                    <apex:outputText value="Email" rendered="{!selectedLanguage == 'English'}" />
                    <apex:outputText value="Email" rendered="{!selectedLanguage == 'French'}" />
                    <span class="small"></span>
                </label>
                <apex:inputText value="{!Contact.Email}" />

                <label>
                    <apex:outputText value="Company" rendered="{!selectedLanguage == 'English'}" />
                    <apex:outputText value="Société" rendered="{!selectedLanguage == 'French'}" />
                    <span class="small"></span>
                </label>
                <apex:inputText value="{!Contact.Account.Name}" />

                <label>
                    <apex:outputText value="Current Title" rendered="{!selectedLanguage == 'English'}" />
                    <apex:outputText value="Titre actuel" rendered="{!selectedLanguage == 'French'}" />
                    <span class="small"></span>
                </label>
                <apex:inputText value="{!Contact.Title}" />

                <label>
                    <apex:outputText value="Phone" rendered="{!selectedLanguage == 'English'}" />
                    <apex:outputText value="Téléphone" rendered="{!selectedLanguage == 'French'}" />
                    <span class="small"></span>
                </label>
                <apex:inputText value="{!Contact.Phone}" />

                <label>
                    <apex:outputText value="Mobile" rendered="{!selectedLanguage == 'English'}" />
                    <apex:outputText value="Mobile" rendered="{!selectedLanguage == 'French'}" />
                    <span class="small"></span>
                </label>
                <apex:inputText value="{!Contact.Mobilephone}" />

                <label>
                    <apex:outputText value="Fax" rendered="{!selectedLanguage == 'English'}" />
                    <apex:outputText value="Fax" rendered="{!selectedLanguage == 'French'}" />
                    <span class="small"></span>
                </label>
                <apex:inputText value="{!Contact.Fax}" />

                <label>
                    <apex:outputText value="Street" rendered="{!selectedLanguage == 'English'}" />
                    <apex:outputText value="Rue" rendered="{!selectedLanguage == 'French'}" />
                    <span class="small">street and number</span>
                </label>
                <apex:inputText value="{!Contact.MailingStreet}" />

                <label>
                    <apex:outputText value="PostalCode" rendered="{!selectedLanguage == 'English'}" />
                    <apex:outputText value="Code postal" rendered="{!selectedLanguage == 'French'}" />
                    <span class="small"></span>
                </label>
                <apex:inputText value="{!Contact.MailingPostalCode}" />

                <label>
                    <apex:outputText value="City" rendered="{!selectedLanguage == 'English'}" />
                    <apex:outputText value="Ville" rendered="{!selectedLanguage == 'French'}" />
                    <span class="small"></span>
                </label>
                <apex:inputText value="{!Contact.MailingCity}" />

                <label>
                    <apex:outputText value="State/Province" rendered="{!selectedLanguage == 'English'}" />
                    <apex:outputText value="État/Province" rendered="{!selectedLanguage == 'French'}" />
                    <span class="small"></span>
                </label>
                <apex:inputText value="{!Contact.MailingState}" />

                <label>
                    <apex:outputText value="Country" rendered="{!selectedLanguage == 'English'}" />
                    <apex:outputText value="Pays" rendered="{!selectedLanguage == 'French'}" />
                    <span class="small"></span>
                </label>

    <apex:selectList value="{!Contact.MailingCountry}" multiselect="false" size="1">
        <apex:selectOption itemValue="" itemLabel="--None--"/>
<apex:selectOption itemValue="United States" itemLabel="United States" /> 
<apex:selectOption itemValue="United Kingdom" itemLabel="United Kingdom" /> 
<apex:selectOption itemValue="Afghanistan" itemLabel="Afghanistan" /> 

    </apex:selectList>
    


    <label>
    <apex:outputText value="Comment" rendered="{!selectedLanguage == 'English'}" />
    <apex:outputText value="Commentaire" rendered="{!selectedLanguage == 'French'}" />
    <span class="small">some extra notes to {!Contact.Owner.Name}</span>
</label>
<apex:inputTextarea value="{!Comment}" cols="50" rows="5" />
<apex:commandButton action="{!Save}" value="Save changes" />

<div class="spacer"></div>
</apex:outputPanel>
</apex:form>
</div>
</apex:page>



that goes with this controller :

public with sharing class SiTFormController2 {
    
    public Contact Contact { get; set; }
    public String Comment { get; set; }
    public Boolean isSend { get; set; }
    public String selectedLanguage { get; set; }
    
    public SiTFormController2() {
        Contact = new Contact();
        isSend = false;
        selectedLanguage = 'English';
    }
    
    public void setLanguageEnglish() {
        selectedLanguage = 'English';
        refreshForm();
    }
    
    public void setLanguageFrench() {
        selectedLanguage = 'French';
        refreshForm();
    }
    
    public void Save() {
        try {
            insert Contact;
            isSend = true;
        } catch (Exception ex) {
            ApexPages.addMessages(ex);
        }
    }
    
    // Method to refresh the form after changing the language
    private void refreshForm() {
        isSend = false;
    }
}