I drove my Camry for about an hour in stop and go traffic. Then I stopped at the store for a couple minutes, when I came out I wasn't able to get the car started. I got a jump, but that didn't seem to work. I was able to gas it while starting, but it eventually went down to 0 RPM. Then I left it there for about 2 hours and I was able to start the car as usual so I drove it home. Any clues on what the problem might have been?

Welcome to the AF!

See if you can access the codes in the ECM (see FAQ for details). If you have codes stored, post them.

Many times, a heat-related problem is attributable to a bad ignition coil or an ECT sensor. You can test both the voltage output and the resistance of the ECT sensor.

http://www.autoshop101.com/forms/h32.pdf

EFI main relay, ignition coil, major vacuum leak after the AFM. Distributor cap/rotor wear/moisture in it.

Is this a serious problem like it has to get fixed immediately? How much would it cost? Am I ok just taking a look at it myself or should i get it inspected?

Duplicate what you did when it happened but, stop at home this time and try to start it. Might want to do this a few times. If it starts ok then leave it alone. If not then head the previous posts. This happened to my daughter in her 94 200 miles away once and hasn't happened since.

You can read any stored fault codes in your driveway but, if you don't want to mess with it I think an Autozone or similar store can read fault codes with a scanner free of charge.

In general, Autozone won't touch a pre-'96 vehicle. It is easy enough to get the codes as outlined in the FAQ thread.

It is your coolant temp sensor most likely if it will not start on a hot start up but is fine on a cold start up and you smell gas when it won't start. The sensor helps regulate the amt of air in the mix.