Administrator password LOST!

Not only does the owner not remember the Administrator password, but no one else has an account on the new Dell Server. I have tried everything that he states could be a password. Caps and lower case nothing works. Now what? I have tried to find LOphtCrack but all leads end in dead-end. There was an Administrator password…I devised it with owner’s help, but I do so many customers I can’t remember them all. So after we transfer ALL data to new server, he waits three months to run software upgrade on new server and no one knows the password. NO ONE! Now what??