The Radio "Anti-theft" code use to given from dealer ( first owner bought the car) If you don't have or lots the code you only can get the code from dealer.
In manual book "Audio Symphony" book have the radio code it calls "Radio card"
Thief!
go to the dealer
To reset the radio code in a 1997 Audi A8, you typically need to turn on the ignition, then turn on the radio. If the radio displays "SAFE," you will need to enter the correct code. This code can usually be found in the owner's manual or provided by an Audi dealership. If you don't have the code, you may need to contact a dealership with your vehicle identification number (VIN) for assistance.
http://www.ibiblio.org/tkan/audi/radios/concert.html
unless you have the 4 digit number you cant...a visit to Audi is the only way
You need the serial number from the side of the radio and also the VIN number. You call an Audi dealership and give them the two numbers and for a $30.00 fee they will give you the radio code to take the radio off of "safe" mode. Lewis Powell
Trouble code P0347 means: Crankshaft position sensor "A" low input (Bank 2)
your code is unique to your car... you'd have to get it from the dealer if you lost it.
You need your operator's folder. In there is a booklet about the radio. it will have a code you need to enter to get the radio out of "safe" mode. the code is unique to each radio and car.
To find the radio code for your Audi A3, check your vehicle's owner's manual, as the code is often printed there. If you can't find it, look for a card or sticker within the glove compartment or the trunk. Alternatively, you can contact an Audi dealership with your vehicle identification number (VIN) for assistance, or use online services that may offer code retrieval based on the radio's serial number.
you turn the key on and off 25 times and the radio works as good as new.
Best bet is to go to an Audi/VW dealership, and have them reset the radio by using a VAGCOM. The other option would be to purchase a VAGCOM yourself (http://www.ross-tech.com/). Of course if you have the actual reset code, you can enter it in manually. I can't tell you specifically how to enter it on the Audi radio, since I have an Audi Navigation system, and the controls are different. But it should be a combination of using Volume and Seek (or other keys the would allow for scrolling) to enter in the code.