HI
need more information
does it turn over but not start or does it not turn over (try to start) at all.
If it turns over but does not start .. I would check to see that the fuel filter is not plugged or the injectors not working.
If it does not turn over then check the battery connections at the battery. Both the battery post and the inside of the cable needs to be shiny clean for it to make good contact.
good luck
tim