'95 base. My key can open the driver side door, but that's it. Passenger and trunk are stuck. The passenger lock work fine from the inside. Maybe The previous owner changed the locks? I dont really care about the why. I'm just looking for advice on the best place to go to fix it. Regular auto repair place? Body shop? GM dealer?
Thanks in advance!

 

I'd call a locksmith and have him re-key the cylinders. I had it done on an eclipse and paid 75$, priced new ones (3) and it would have been 150$.

 

Either the locks were changed, or the cylinders are corroded stiff. If they're corroded, a locksmith isn't going to be able to do a "simple" re-key. Have you tried soaking the cylinders with PB Blaster, and working the key back and forth to see if it wants to budge at all? Been there before with more than one frozen cylinder, but was able to free them up after removing it from the door, soaking it, and heating it with a torch. When these pot metal cylinders get corroded stiff, it may as well be welded.