The system manager can extend it. Fill in one of the applications forms in the corridor. Don't play with this directory or you will be unable to log on the next time. You have changed the access rights to your home directory, thereby denying access to yourself. Same as above.
Passwords are case-sensitive.
Check whether CapsLock is on. When typing your user name, make sure you did not leave a space, tab or other invisible character at the end. You are trying to log on to the wrong domain, or to log on to a local account. Your account may have been deactivated by the system manager because you violated the user rules. Send e-mail to him.