Make sure battery is really charged. You need a good twelve volts to the ignition and the computer, if it is just barely turning over it won't be good enough. If it was running when you parked it it should have spark. Check that you can hear the fuel pump run when you turn the key, if you can hear it check pressure at rail. If you have good fuel pressure pull your plugs and see if they are fouled. My son's car was parked for about 2 months for a motor issue and when we got that all fixed the fuel pump would not run, so they can go bad while sitting. Your gas could also be stale, drain and fill with fresh.