2003 Pontiac Grand Am 2002 Pontiac Grand Am suddenly won't

2003 Pontiac Grand Am 4 cyl Automatic

Car is driven daily. Drove it to the car wash today then home, parked it for about an hour and went out to start it and it wouldn't stay running. It would either not start at all or it would turn over but would putter out within 2 seconds.
This is sudden, no prior warning or problems. Drove just fine one hour prior.

What is the problem and what needs to be done to fix it?

Thanks