My radio stopped working in my 1999 Pontiac grand prix, ever since then my dash lights won't work and my main headlights dont work but my running lights do. are these 2 related? What could cause it?

Sounds like you have an electrical problem. Start with the fuse box. It's located in side of the glove box to the right side.

By chance does your grand prix have an aftermarket radio in it? If so do you know who installed it.

It has the stock radio in it. can I go to a local auto parts store and can they tell me what fuses are bad???

They might be able to tell you. Sorry, I don't know? It sounds like it could be multiple problems. Does the radio not play at all or just the display not light up?

When you take the cover off from the fuse box if you flip it over it should tell you which fuse goes to the radio after you locate the fuse take your fuse puller if have one or take pair of pliers and pull when looking at it you should be able to tell if it is blown the middle will be burnt into

All the fuses are good and in working order, my biggest issue is my headlights dont work. I took it to my shop and they cant even figure out whats wrong with it.

I would start with the head light switch. Replace that and see what it fixes. It might just take care of all of your problems.