I am working on a motion computing tablet for a friend, they got locked out of admin account. I managed to get a limited account active but i cant get access back to admin account.

Things i tried :
Connecting disk drive with install disk
Running Ubuntu from Flash drive to rename the sethc file to cmd
Used the net user user name* method from limited account
Tried to get the startup repair hack to work

Nothing worked. Does anyone know what else i could do to get access back to admin?
I googled everything nothing helpful is coming up.

It is running Windows xp Tablet PC Edition (blast from the past).

Thanks.