The first step in ensuring you don’t lose anything valuable at Oktoberfest is to leave all your non-essential valuables at home or to check them in at the bag check at the start of your Oktoberfest visit. There is a bag check directly to the right of the southern exit of the Theresienwiese U-Bahn stop.
If you do manage to lose something, it may turn up at the Wiesnfundamt (Oktoberfest Lost and Found). Every year, thousands of items are turned in and often picked up including, but not limited to: phones, wallets, keys, bras, backpacks, dentures, musical instruments, and countless other items that can be lost while in the beer tents, on bumper cars or on the Ferris wheel.
Did you know in 2013 a man lost his car at Oktoberfest for five weeks?