Frank has been using the same password for years and now suddenly the password won't work on his Windows Surface. Could the hard drive be going out? Leo says that it's more likely a keyboard issue. He should check the CAPS lock, SCROLL lock and NUM lock to make sure they aren't enabled. Another thing to do is enable the feature that will allow him to see his password as he types it.
Leo says that Frank's PC has a blank, hidden administrator password in Windows 7 that he could use to get in and change his password back, in case it's been changed. He should Google "Hidden Administrator password" (which is blank). He can also run SpinRite to test his hard drive, but he'll need to do it from a USB Key by installing it with UNETBOOTIN. That will enable him to install SpinRite on a USB key or CD ROM, and then boot to it.
The chatroom also thinks it may be a corrupt profile. This is also why it's a good idea to have a separate admin account and run as a general user. That way should his account get compromised, he can go into the admin account and clean things up.