One day you may go to open your hood, only to feel a snap in the lever, then no resistance and no open hood. Your release cable has snapped. You can still get the hood open. Over each headlight you will be able to see the latching posts. Use a long flat head screwdriver to push the latches to release them. Be careful not to crack your headlights while forcing the latches. You can also use a bent coat hanger to grab the latches and release them. Note that to release each side you push/pull towards the center of the car.
To replace the cable, you can buy one from Audi, or you can get a cheaper one by going to a bicycle shop and getting a shifter cable for a tandem bike. If the original sheath is damaged, you can get one of those, too. You'll probably have to cut down the length and put some crimps on the ends, but the finished product will likely last longer than the original.
