My car is 96 a4 2.8.
Anyways, after my battery was re-connected, my car's stock stereo system is *beeped* up. Even though, I entered the right codes, it's not unlocking. Also, i know this is a right code because i got it when I bought the car. Also, it's not unlocking for me to put in codes again for 3 days now... No stereo is making me miserable, someone help me PLEASE

Turn radio on, SAFE appears
Press the buttons FM & DX at the same time and hold until 1000 appears in the display.
You enter the code by pressing the 1-4 buttons multiple times.
i.e. if the code is 3231, then press 1 three times, 2 twice, 3 three times and 4 once.
The code will be shown on the display.
The press FM & DX at the same time and hold until SAFE appears again, then release both buttons and the radio will come on in a few seconds..
Many people make the mistake of just typing the code in using the 1-6 buttons (as long as they don't have digits 7-9 in the code). This won't work. Only buttons 1-4 are used to enter the code.
It could be that you've arsed up the code entry but you should be able to enter the code again after an hour as long as the unit is left powered on. If this still doesn't work, I'd disconnect the battery again for about 15mins and let everything reset and try again.