I bought an Audi A3 secondhand with audi chorus Blaupunkt-WERKE GMBH 7648 245 380 SERIEL NO AUZ1Z2X678588 ,the radio is on a safe mode please help me with the code and the method to enter the code

You must retrieve the code that comes with the Audi's radio unit. To change to safe mode:

1. Turn on radio. The radio display shows "SAFE".
2. Press the P.Scan and RBDS buttons simultaneously and hold until "1000" shows on the display. Release the buttons. Do NOT press these buttons again, otherwise the radio will consider "1000" to be the code.
3. Use Preset buttons 1 ... 4 to enter the four-digit code number from your radio card. Preset button 1 corresponds to the first digit, Preset button 2 corresponds to the second digit, etc. Each press of the button increments the number by 1.
4. Once the code shown on the display is correct, press the P.Scan and RBDS buttons simultaneously and hold until the word "SAFE" appears in the display, then release the buttons.
5. The radio should unlock and be usable shortly afterwards.
6. If an incorrect code is entered, the word "SAFE" appears, first flashing and then continuously. You can repeat the above steps to unlock the radio once more, the number of attempts will be shown in the display. If an incorrect code is entered again, you radio will be locked for about one hour. After one hour - the radio must stay on and the key must remain in the ignition lock - if the display goes out, the you can repeat the above procedure to unlock again. The cycle - two attempts, one hour lock-up - still applies.
7. If you lose your radio code, contact your Audi dealer.

Also, if you don't have your radio code, VW/Audi put them under the trunk floor mat, on top of the info sticker. The dealer is supposed to move them to the manual, but needless to say, it doesn't always happen. If you don't have the card in either of those two places, you will have to go to an Audi dealership, and have them plug our radio into their scanner, and have them input the code for you.