CD player - 1999 Eclipse GS

I recently (past week) had my transmission in my 1999 Eclipse GS replaced. When the car was returned, my radio needed a code to be activated. Me, being stupid, pressed one to many buttons, and now, when you turn on my cd player the display shows "off." Can anyone please tell me how to activate my cd player

Call up a dealership

they should give you the codes for free.