97 golf won't start

Please help. I drive a '97 5 speed golf. One day I drove home from work without any problem, (except the coolant light was on), I parked, turned her off, added coolant and 3 hours later was unable to start her again. She cranks like she wants to start but can't. Timing belt is fine, ignition coil is all good. I can't rule out fuel pump, but she wouldn't even turn over when I sprayed some starter fuel into the intake valve. There's a good spark on the distributer cap and all the fuses work. Please, does anyone have any ideas? I'm too poor to buy a new car and can't afford a mechanic right now (I'm already replacing the transmission in my Nissan Quest).
I was having trouble with her stalling frequently recently...O2 sensor needs to be replace. You think these are related?

HELP!!!!

A bad O2 won't keep it from starting. Make sure there is spark all the way through the plug wires @ the plug, not just at the coil wire. When the key is turned to on position the fuel pump should run for a few seconds, and for a couple seconds after canking. If not, check that first (relay, pump). If both those are good & it won't even try when sprayed with starting fluid suspect engine timing is off (timing belt alignment). Did it overheat?

Turned out the timing belt had slipped out of place. I replaced it since I had it all apart anyway and she turned over immediately. There is so little wear in the belt I never would have figured it was the problem at all. Guess I need to trust my first instincts in the future.
Thanks for your help.