If the system Administrator account is the only option showing at the login screen, your own account has probably had a failure in the Profile. Most systems don't require a password for the Administrator account so try leaving that blank and just hit the Enter key.
If you can't get in that way, restart and tap the Function 8 key and select Safe Mode with Networking. Your own account might show up and if it does, run your anti-virus programme and delete anything it finds.
If that also fails, ask for the password from everyone who might have set it. We can't help you further than that because we can't see proof of ownership. Take it to a professional PC fixer and show them that proof and they can remove the hard disk, rescue your data and make a fresh installation of whatever version of Windows you had before.