Audi A4 date display - Halmer
This has disappeared on my mate's A4 and now he can only view the time. His service book is in German which doesn't help. I think that his wife has meddled with the settings on the dash.

Does anyone know how to restore the date to show please?
Audi A4 date display - volvos60T5SE
Disconnect the battery for 5 minutes, that should solve it!
If it is a TDi It will run as rough as pink fluffy dice for the first 5 miles, it did on my galaxy TDi pd 130 anyway, i imagine that it would be the same on the audi, as they are the same diesel engines!

Hope this has helped!
Audi A4 date display - Buster Cambelt
Try pulling the left button on the dash display and turning it back and forth. That should reset it. Some Audis have a clock / date that is supposed to be reset by the RDS signal but I have never found a UK one that does. It is possible to fool the clock into displaying nothing until it gets the right signal, sorry can't remember how this happens.
Audi A4 date display - Halmer
As far as I can recall B it's not a button like in a Passat. There are two rounded plastic thingys that can only be pressed in. I expect that that I have to be pressed in a certain sequence or something.
Audi A4 date display - Buster Cambelt
A new shape one then? Sorry, was thinking about the old one.
Audi A4 date display - Dulwich Estate
Keep pressing the "Mode" button. You'll get to where you want to be soon enough.