look at how key 2 & 3 are setup and understand the logic pattern and apply it to the rest of the voids.

private void Key_2_Click(object sender, EventArgs e)
{
    try
    {
        if (!Directory.Exists(LocationKey))
        {
            Directory.CreateDirectory(LocationKey);
        }

        if (File.Exists(LocationKey + @"\Slash.wav"))
        {
            File.Delete(LocationKey + @"\Slash.wav");
            File.Copy(audioFilePath, LocationKey + @"\Slash.wav", true);
            KeyStrings[1] = LocationKey + @"\Slash.wav";
            Key_2_SLASH.ForeColor = Color.Red;
        }
        else
        {
            File.Copy(audioFilePath, LocationKey + @"\Slash.wav", true);
            KeyStrings[1] = LocationKey + @"\Slash.wav";
            Key_2_SLASH.ForeColor = Color.Red;
        }

        LookButton.Focus();
        LookButton.Select();
    }
    catch
    {

    }
}

private void Key_3_Click(object sender, EventArgs e)
{
    try
    {
        if (!Directory.Exists(LocationKey))
        {
            Directory.CreateDirectory(LocationKey);
        }

        if (File.Exists(LocationKey + @"\Multiply.wav"))
        {
            File.Delete(LocationKey + @"\Multiply.wav");
            File.Copy(audioFilePath, LocationKey + @"\Multiply.wav", true);
            KeyStrings[2] = LocationKey + @"\Multiply.wav";
            Key_3_MULTI.ForeColor = Color.Red;
        }
        else
        {
            File.Copy(audioFilePath, LocationKey + @"\Multiply.wav", true);
            KeyStrings[2] = LocationKey + @"\Multiply.wav";
            Key_3_MULTI.ForeColor = Color.Red;
        }

        LookButton.Focus();
        LookButton.Select();
    }
    catch
    {
    }
}

private void Key_4_Click(object sender, EventArgs e)
{
    if (!Directory.Exists(LocationKey))
    {
        Directory.CreateDirectory(LocationKey);
    }

    Key_4_MIN.ForeColor = Color.Red;
    KeyStrings[3] = audioFilePath;
    File.Copy(audioFilePath, LocationKey + @"\Subtract.wav", true);
    KeyStrings[3] = LocationKey + @"\Subtract.wav";
    LookButton.Focus();
    LookButton.Select();
}

private void Key_5_Click(object sender, EventArgs e)
{
    if (!Directory.Exists(LocationKey))
    {
        Directory.CreateDirectory(LocationKey);
    }

    Key_5_SEVEN.ForeColor = Color.Red;
    KeyStrings[4] = audioFilePath;
    File.Copy(audioFilePath, LocationKey + @"\Seven.wav", true);
    KeyStrings[4] = LocationKey + @"\Seven.wav";
    LookButton.Focus();
    LookButton.Select();
}

private void Key_6_Click(object sender, EventArgs e)
{
    if (!Directory.Exists(LocationKey))
    {
        Directory.CreateDirectory(LocationKey);
    }

    Key_6_EIGHT.ForeColor = Color.Red;
    KeyStrings[5] = audioFilePath;
    File.Copy(audioFilePath, LocationKey + @"\Eight.wav", true);
    KeyStrings[5] = LocationKey + @"\Eight.wav";
    LookButton.Focus();
    LookButton.Select();
}

private void Key_7_Click(object sender, EventArgs e)
{
    if (!Directory.Exists(LocationKey))
    {
        Directory.CreateDirectory(LocationKey);
    }

    Key_7_NINE.ForeColor = Color.Red;
    KeyStrings[6] = audioFilePath;
    File.Copy(audioFilePath, LocationKey + @"\Nine.wav", true);
    KeyStrings[6] = LocationKey + @"\Nine.wav";
    LookButton.Focus();
    LookButton.Select();
}

private void Key_8_Click(object sender, EventArgs e)
{
    if (!Directory.Exists(LocationKey))
    {
        Directory.CreateDirectory(LocationKey);
    }

    Key_8_PLUS.ForeColor = Color.Red;
    KeyStrings[7] = audioFilePath;
    File.Copy(audioFilePath, LocationKey + @"\Plus.wav", true);
    KeyStrings[7] = LocationKey + @"\Plus.wav";
    LookButton.Focus();
    LookButton.Select();
}

private void Key_9_Click(object sender, EventArgs e)
{
    if (!Directory.Exists(LocationKey))
    {
        Directory.CreateDirectory(LocationKey);
    }

    Key_9_FOUR.ForeColor = Color.Red;
    KeyStrings[8] = audioFilePath;
    File.Copy(audioFilePath, LocationKey + @"\Four.wav", true);
    KeyStrings[8] = LocationKey + @"\Four.wav";
    LookButton.Focus();
    LookButton.Select();
}

private void Key_10_Click(object sender, EventArgs e)
{
    if (!Directory.Exists(LocationKey))
    {
        Directory.CreateDirectory(LocationKey);
    }

    Key_FIVE.ForeColor = Color.Red;
    KeyStrings[9] = audioFilePath;
    File.Copy(audioFilePath, LocationKey + @"\Five.wav", true);
    KeyStrings[9] = LocationKey + @"\Five.wav";
    LookButton.Focus();
    LookButton.Select();
}

private void Key_11_Click(object sender, EventArgs e)
{
    if (!Directory.Exists(LocationKey))
    {
        Directory.CreateDirectory(LocationKey);
    }

    Key_11_SIX.ForeColor = Color.Red;
    KeyStrings[10] = audioFilePath;
    File.Copy(audioFilePath, LocationKey + @"\Six.wav", true);
    KeyStrings[10] = LocationKey + @"\Six.wav";
    LookButton.Focus();
    LookButton.Select();
}

private void Key_12_Click(object sender, EventArgs e)
{
    if (!Directory.Exists(LocationKey))
    {
        Directory.CreateDirectory(LocationKey);
    }

    Key_12_ONE.ForeColor = Color.Red;
    KeyStrings[11] = audioFilePath;
    File.Copy(audioFilePath, LocationKey + @"\One.wav", true);
    KeyStrings[11] = LocationKey + @"\One.wav";
    LookButton.Focus();
    LookButton.Select();
}

private void Key_13_Click(object sender, EventArgs e)
{
    if (!Directory.Exists(LocationKey))
    {
        Directory.CreateDirectory(LocationKey);
    }

    Key_13_TWO.ForeColor = Color.Red;
    KeyStrings[12] = audioFilePath;
    File.Copy(audioFilePath, LocationKey + @"\Two.wav", true);
    KeyStrings[12] = LocationKey + @"\Two.wav";
    LookButton.Focus();
    LookButton.Select();
}

private void Key_14_Click(object sender, EventArgs e)
{
    if (!Directory.Exists(LocationKey))
    {
        Directory.CreateDirectory(LocationKey);
    }

    Key_14_THREE.ForeColor = Color.Red;
    KeyStrings[13] = audioFilePath;
    File.Copy(audioFilePath, LocationKey + @"\Three.wav", true);
    KeyStrings[13] = LocationKey + @"\Three.wav";
    LookButton.Focus();
    LookButton.Select();
}

private void Key_16_Click(object sender, EventArgs e)
{
    if (!Directory.Exists(LocationKey))
    {
        Directory.CreateDirectory(LocationKey);
    }

    Key_16_ZERO.ForeColor = Color.Red;
    KeyStrings[15] = audioFilePath;
    File.Copy(audioFilePath, LocationKey + @"\Zero.wav", true);
    KeyStrings[15] = LocationKey + @"\Zero.wav";
    LookButton.Focus();
    LookButton.Select();
}