Trunk won't lock on my 1996 Buick Skylark how do you repair it or what is the estimated cost?

In the fuse block check the door lock and unlock fuses. Then open the trunk with your key. Test the wire when you push your remote and see if the lock gets power. If it does then its probably a bad lock. Ifnot it can be a m odule. One thing though make sure your battery int eh remote is good as that can effect it.