Restart and tap Function 8 then select Safe Mode with Command Prompt. When the black form shows up type
net user /a fred coffee
including all the spaces,then press Enter. Restart into Normal Mode (by doing nothing) and your login page will show the new account named fred and the password you need is coffee (I'm drinking one now, hence the suggestion).
Log in then press the Windows key and R together and into the open box, type regedit then press Enter.
Navigate to H_KEY_LOCAL_MACHINE\Software\Microsoft\WindowsNT\ProfileList then find the account with the long reference number that applies to your own login - not fred's. If you have a entry with the same name but with the suffix .BAK, select the entry without that extension...