Depends on the type of radio you have.
Some have to be re-programmed through a dealer, others I can help you with.
Does your radio look just like this...
You need to pull the two 3-digit codes from the radio.
1. Press and hold presets 2 and 3 for about 5 to 10 seconds until you get 3 digits on your display. This is the first 3 of 6 digits you will need, so write 'em down. 2. After doing step one and writing down the code, immediately press the AM/FM button to get the last 3 of the 6 numbers you'll need, and write 'em down. (if you wait too long between steps 1 and 2 and the LOC code displays again, just start over).
Post me the codes after you get them, and I will try to get the unlock code for you.
Your radio code is 0400...
Use the hour and minute buttons to enter this code, then push the AM/FM button, and it should work.