How did you change the password back? Did you do it from within the account in question or as the Administrator? If as the Administrator, try changing it back again while already logged into the account.
If that doesn't work, and you don't have either a Password Recovery Disk or a user set up with Data Recovery rights, (the disk or the user rights must have been created while you still had access to the files
) then I'm afraid your files are not recoverable.
Edited by Amazing Andrew, 18 February 2010 - 01:11 PM.