We bought tv from thrift store and it has a lock

http://www.retrevo.com/support/Toshiba-13A24-TVs-manual/id/311ag616/t/2/
you can download the manual from this site for free by clicking the Get Manual button. You do not have to enter your email address.
The answer is at the bottom of page 10. "if you forget or lose your password"
This is a PDF file. You may have to download Adobe Acrobat Reader for free at www.adobe.com in order to view it.