1997 GMC C1500 Truck won't turn on!

Drove the truck on a wednseday and truck ran fine and didn't realize the truck was on empty till two days later. So when I went to turn the truck on it would turn over but wouldn't turn on, so I figured I'd put some gas in and try to turn it on again. After the gas was put in I turn the key on and off about three times so the fuel pump could suck in some gas thinking the truck would then turn on, but instead I got a back fire that sounded like a shotgun went off. Another thing I noticed when I started looking under the hood was that I smelled gas. I don't know If this has something to do with the problem or this could be a whole different problem. As I was under the hood I figured I'd check the spark plugs. When I pulled one out I notice the end of the spark plug was wet and smelled like gas so I decided to check the cable to see if it had any spark, and it did. This truck means alot to me as it was handed down to me. So if you guys have any clues or Ideas to what y'all think is going on please give me a shotout.
Thanks,
Rolando Gonzalez