Engine won't fire up! Options

[X_RunnerGT]

So recently my car stopped wanting to start. I turn the key and the starter cranks continuously,but it won't turn over? I left my key in the ignition, turned, yesterday and it fired up. Once it's started and it's been running for a while it'll start, but now nothing? Any ideas about what I'm dealing with. I've been told the timing belt, the fuel pump, fuses, which from the ones I've checked are all good. Any help would be appreciated...

[X_RunnerGT]

Well I own a code reader and it isn't throwing any codes. That's good advice I'll have to look into all of that.. I pulled one of the plugs yesterday to check for spark and I thought I saw it spark.... Odd thing is when I had the plug and wire pulled it turned over, go figure? Then I pulled all the rest of the the plugs and wires and inspected them, they made need replacing. I had the positive battery terminal removed too. After I reassembled everything it fired up... I let it run for a moment and turned it off and then attempted to start it but nada...