changed the radio and now my car won't start ?

Hello, I can't find any correlation whatsoever with the audio unit and the vehicle starting. The only thing I could think of would be some kind of blown fuse related to both the audio unit and a component that is essential in allowing the vehicle to run. This could be from a momentary power surge in the related wiring circuit. It's a wild guess, but definitely start by checking all fuses. Perhaps you'll get lucky! If not, you'll have to do normal testing to determine why there is no starting. https://repairpal.com/auto-repair-near-me Click the link or call us at 877-913-1554. We'll gladly find you a certified RepairPal shop in your area.