You changed your battery in your 1998 Buick lesabre now your radio wont work it reads loc that's all it does now what do you do?

You have four options I can think of off hand.

One get in touch with whoever set the code and ask them for the code then input the code.?

Your second option is to speak to your local Buick dealership and ask them about unlocking the radio.

Third option is to get an unlock code from a third party.

Fourth option is to buy another radio.