Usually no reverse requires rebuild to fix.
1.. If it will drive forward see if it has 3rd. They share a common componant.
2.. Also as you drive forward "throw"it in manual low to see if it "engine brakes".
If either one of these is the case then you need a new trans. If #1 then you have direct clutch problem. If #2 you have low & reverse problem. NOte: these terms (low and reverse and direct clutch) are "transmission industry terms". VW specific terms may differ.