How can I unlock the radio on my 2002 Blazer

check the owners manual for a code . or you can go to the dealer with the VIN & a fee.

So I looked in the manual for the code for my 2002 Chevy Trailblazer and there is no code listed it says take to the dealership if air or lock occurs which that is exactly what's happened it says it's locked I went to YouTube try to couple different videos and nothing seems to work

I have a 2002 Chevy Trailblazer the radio says it's locked there is no code in the manual it says take to a dealership if it says locked I went to YouTube and checked out a couple of different videos but how they said to do it neither one of them are working they said Hold the two and three down at same time for 10 seconds I held it down for 15 seconds nothing happened