MY MODEL # PVC RX540 A BOX APPEARS WITH THIS INFORMATION. THIS COMPUTER IS IN USE AND HAS BEEN LOCKED ONLY VAIO/BILL OR AN ADMINSTRATOR CAN UNLOCK THIS COMPUTER USER NAME (BILL) PASSWORD (UNKNOWN} I TRYED OLD AND NEW PASSWORDS AND NONE WORKED.

Hello,

Try to press reset or the power button to restart the PC.

when the box appear. Press "CTRL+Alt+Delete" two times successive.

then it Prompted you to type the username and password.

In the;

Username: type "administrator"
Password: leave it blank

and then "enter" or click ok.

If this successfull then you can change the password of bill or any users in this PC.

By changing password:

click run and then type: "control userpasswords2" and then enter.

bring you to the username windows. then you can change the password or delete the username.

But if this solution is not successfull:

Microsoft has no recomendation to solve the issue at all. because that is the protection of the users.

you have to reformat and reinstall the oerating system.

may this help;

melnavz

PS:
pls do not rate me if my solution not solve the issue and you need more further information. but if is invaluable solution rate me fixya.