Theftlock feature

I changed the battery in my 2002 Sonoma today and the theftlock engaged on my radio panel (LOC). After attempting to unlock the panel with random codes I got an (INOP) displayed on my panel. I do not know the code nor did I know it even had a code. The truck was purchased from and individual whose contact info I do not have. Can anyone help me with unlocking my radio?

your gonna have to bring it to a dealer and have them reset your code using your VIN #. Will be like $75, but its easier just to buy an aftermarket headunit so you dont have to worry about this problem anymore.