Truck won't Move

My 1994 Mazda B3000 won't move. The engine turns over, but it won't reverse or move forward. When I try to rev the engine (the truck acts like something is holding it in place), the engine dies. Is this a transmission problem? How expensive can this repair get?
I'm worried about having to get more repairs; three months ago we paid a local mechanic $1000 for various repairs (we had to save up for a year to pay it), only to later discover that they didn't perform most of the repairs at all (we will be taking him to court). How can I find a GOOD, reputable mechanic in my area? Neither my husband nor I is mechanical at all, and we don't know anything about vehicles.

Thanks!