So it's actually cranking, and not just clicking? The common problem is bad contacts in the starter causing the starter to randomly not work. Taking it out and putting it back in is fairly straight foward, it also helps alot if you have some small arms
You'll want to jack the car up enough so you can get under the drivers side, then take a bunch of extensions with some universals, a 14mm wrench and socket and unbolt it. Use the wrench to hold the nut still, and unbolt the bolt with the socket and extensions, or which ever you find easier. When you get a new starter ask for a 91-92 unit, it has threads built in so you don't have to hassle with the nut, just the bolt. Also you can't get the wires mixed up since theres only 2 of them, and there two different sizes.