the other day i tried to start my truck and nothing... no lights, no nothing. After i got a jump start it ran/runs fine and starts up with no problem.

I'm assuming this is the battery and not the alternator or anything else? And also, why would it have not started at first, but runs fine now?

 

Your alt could be improperly charging your battery. What is it's output when running? Most places like autozone will test the alt/batt for free.