Truck won't start.

Truck won't start? Replaced the Crank shaft position sensor, and the fuel filters and the truck still won't start. I was driving along when all of a sudden I would press on the accelerator and nothing would happen. It no longer wanted to go forward. Would die if in gear, but would idle rough. So we changed the fuel filters (both), then the computer read that the Crank Shaft positioning sensor was the problem, so we replaced that and now it won't start at all! Help please?