In need of advice/troubleshooting

Heres the deal:
I've got a 96 VW jetta gl 4cylinder.
My girlfriend was driving it, and it basically just turned off and she coasted into a parking lot. However after this the radio/other electronics would work it just wouldn't start.
So.. several mechanically minded friends of mine looked at it and coming to differant conclusions, So we:
first checked fluid levels,
replaced the fuel filter,
removed the battery and checked it,
replaced several sparkplugs,
These simple fixes were unsuccessful..My friends last diagnosis was that the head gasket was blown, and also the water pump was trashed..due to there being evidence of fluids leaking where they shouldn't ect..
I'm not sure if this is enough info, but if anyone has any other ideas of possible things to look for/try i'm kind of at a loss due to my inexperience.

I would check the coil pack and the ignition switch. Both parts like to get cracks in them and cause the car to not start and/or cut off when driving.

Was it raining when the car cut off?