Is the battery fully charged?
If you reckon it is, you might try this trick as a long shot...disconnect the battery for half an hour or so, then hook it back up and see what happens. You could have a charger hooked up to the battery while it's disconnected, just to give it some more zap.
Might be a good idea to have your radio security code handy...just in case.
Not sure this method will work with a VW, but I've used it on lots of other makes and it has worked a treat.
And all it will cost you is a bit of time!