So I go get into my always reliable always starts 03' Altima to go to work,turn the key it starts to light/start I let go of key(too soon i think)it doesnt start. i let it sit a minute tried again to start but just cranks & cranks. Never even tries to fire again. I get home from work 5hrs later,after 3 attemts if finally starts. My question is what could have caused this hard start issue? dont want to get stranded somewhere. Where do I start in order to fix/prevent from happening? Thanks for any help.

what have you tried? more than likely its plugs, when did you last replace them? actually it could be just about anything too. i would check for a spark and squirt some cat safe carb cleaner in the Throttle body , check fuel pressure all the usual stuff.