99 Oldsmobile Silhouette ran fine at first. Van started missin' and cutting off, then I replaced spark plugs.?

It ran fine for one day and a half..When I got home . I tried to crank it and now it won't crank. It is getting gas and the lights and everything is coming on. Any suggestion on what could be wrong? When I bought it someone had cut catalytic converter off and replace with a straight pipe. Now it won't crack. Help?!

2015-11-09T11:06:19Z

okay...it is spinning over but it won't crank up...

Anonymous2015-11-09T10:34:05Z

The lights illuminating doesn't mean there is enough amps to rotate the starter. Try a jump start. If it starts you probably need a new battery. But check that the alternator is charging first.