So this is kind of an amusing story, so even though it's mostly unnecessary, I'll go ahead and share it.

My friend has a 1998 (or 1996? I know it's important-ish because of the facelift, but I can't remember off the top of my head, hopefully it's not important for my line of questioning) A4 1.8T Quattro that he bought used from a private owner quite a while back. Pretty darn good condition, miles are around 130k, no check engine light or major problems. Only real problems were a few interior leaks.

One day, he went outside to get into his car, using his key fob (as usual) to unlock it. Didn't do anything. Now, apparently since the day he bought it, he has 100% used the key fob to lock/unlock it. Makes sense I suppose, it's convenient. Personally I've never had a car yet with a key fob. So naturally, he automatically assumed the key fob battery was dead. Popped the battery, put a new one in, tried it... No go. Apparently the car battery is dead. Well shoot, he says. Goes to unlock the driver's door.... Lock won't turn. Same with the passenger side and trunk.

So apparently, the previous owner had the ignition lock cylinder (most likely) changed and didn't include a key for the exterior locks. My friend had a locksmith unlock the car, but as you may have noticed, he popped the battery on the key fob, so now it's deprogrammed. He now has no way to lock or unlock his car. Haha ouch.

So my thought is the best way to fix this is to replace the lock cylinders, but I'm not really familiar with audis (or really replacing multiple lock cylinders. I've replaced the door on an old Mercury Tracer and swapped the lock over, but there wasn't anything like a security system or power doors).

So any pointers or thoughts on this? I'm not even sure where I would get a full set of lock cylinders (with a matching key). Do junkyards do that? Is it something I can get online? Is there any issue with there being power locks and security?

Thanks for your help!