I've got a 2007 A6. It ran out of gas and after putting 3 gallons in it will crank but it won't turn over. Any help would be appreciated. Thanks in advance!

 

I would try to prime it a few times and add more fuel to make sure there is enough to fill the pump up. Once it runs dry it's possible you have air in the lines now - that's where priming comes in. Turn the key to the 2nd position (before crank, where all the lights come on), let it sit for 3 secs and turn it back off again. Do this 5 times and see if it will start.

If that didn't help, check fuses for the fuel pump and if they look good, start looking to replace the fuel pump that's in the tank. It uses the fuel to cool itself and when you run it dry it could have overheated and failed (looking at the age of the car even more likely). If you end up getting a new pump, make sure you replace the fuel filter as well.