I left my iphone in the car and it got really hot and now it wont turn on

This means the device was reset to factory settings. You need to connect the device to iTunes. Go to a Mac or PC with iTunes, start iTunes and connect iPhone to the Mac/PC and follow on-screen directions. You will need to reestablish your iTunes account to the iPhone for apps and music (assuming you use iPhone for apps and music). If you have only download apps/music to iPhone and never performed a sync/backup to iTunes (really bad idea, BTW), I would suggest making an appointment at apple.com with the Genius bar at a local Apple store.

In simple terms, the starter gets hot from a high amount of voltage flowing thru it.
The why part is another thing.
Could be a bad connection between the starter and the battery including the ground. Could be a problem with the engine not wanting to turn over. For example, if you broke a timing belt the engine may lock up.

It sounds like you need to take it to Apple for replacement. No iPhone should get hot to the touch during usage. You can schedule an appointment here: http://www.apple.com/retail/geniusbar/ If it is still in warrantee, you shouldn't have any problems.

there is a hardware issue. Apple should give you a replacement. If you're out warranty, you can try to open it and replace the logic board. You can get the part at iPad Repair and there is a guide that shows you how to open a kindle and install parts at iPad Repair Guide.

I had this problem a few months ago. I shut it down and removed the battery over night, and it was fine when I turned it on the next morning.

plz change ur charger

try to go to your iphone settings

check tthe back of the iphone is it hot if it is let it sit until it isnt then plug it in if that doesnt work put the phone into dfu mode (Hold the home button and plug in the usb cable into the fone

This is usually a manufacturer defect, if the battery has any problems i can short circuit and cause major damage inside the phone. Lithium Ion batteries have a very hot current so this is likely. Apple is completely responsible for the phone if the warranty is still good. Try to do a master reset or take it to an apple store and find someone who is capable of recovering the data, I have tools to read that hard drives from ipods but the memory in the iphone i think is hard wired into the board. Try to use the charger as well, and see if the charger gets hot, then you probably have a short in the power circuit in the phone.

hold power button and home key as soon as u see apple logo let go of power button but keep holding home key this will put iphone in recovery mode then sync n recover