my neon wont start. it turns but wont start. i think it has something to do from when my bro was tightening the negative battery cable and accidently touched the positive terminal with a wrench. what can that harm to stop the car from starting????

PCMs are normally pretty tough - but:
That much of an electrical jolt (from normal 12 volts to zero and back to 12 volts) might have been enough to have injured some CMOS electronics in the PCM. Try getting, even borrowing, a PCM and swap it out for yours. I wouldnt buy a new one, they arent that hard to get from salvage yards and on ebay. It takes about 20 minutes to change one. First you disconnect one of the battery cables though! The hard part is working the connectors off the end, and getting the PCM pulled out around the wiring harnesses that run past it. I got one on ebay for $20. It works 95%. (It wont turn the fans on when the engine gets hot, but is a good unit to have for 'testing'.

While you are looking for a cheap PCM, check all of the wires between the battery posts and what they run to. These cars have several ground wires, all of which are important. One of them might have been half-burnt by the high current.

ok.. wait. before you do that, make sure you didnt just 1)fry the battery or 2) fry a fusible link/fuse

check all your fuses, check to make sure youre getting 12v to the starter, check the battery to make sure youre getting power at ALL.. and then, finally, make sure the fuel pump is turning on..

if could be a simple wire prob!! look for fried/smoked/smelly things too

Good Points; if the fuel pump doesnt hum softly for about 2 seconds when the ignition key is first turned to the on position (but not to the start position yet) then you wouldnt have fuel pressure. The hum would be hard to hear unless its fairly quiet. If you do hear the fuel pump run, the next thing to check would be whether you have spark to the plugs or not. You could pull one of the plug wires out, put an old spark plug into it, and let it lay on the top of the engine. When the starter is cranking the engine over you should see a bright blue spark jumping at the electrodes.
Let us know how it goes...