2006 Nissan Frontier won't star

Engine Performance problem
2006 Nissan Frontier 6 cyl Two Wheel Drive Automatic 138000 miles

The truk was runing fine until day before yesterday, the engine die when driving but started back on with no problem. The following mornig it did not start. I check for spark and most of the time there isn't any, I check for signal at the ingectors and trere is allways a signal. I put new sparks and battery, and stile same problem.