Diesel 1994 Jetta GL

Hey Out of the blue, my jetta began becoming hard to start... then the next day it didnt start at all, it will crank but not turn over. I have checked the fuel system and it seems to be normal, so im thinking possibly electrical or mechanical. #2 I dont have any wiring diagrams or service manuals to refer to so I have no idea where to start... any ideas on either of my problems?? thanks...:banghead: