after replacing the alernator the car wont start
Does it turn over or is the car totally dead? Check the battery terminal connections and make sure they are clean and tight.
It is completely dead.
Check the battery cables and battery, connections and wiring like F_O_R suggests. You can always have the alternator and battery tested at the parts store.
Looking for a Used Passat in your area?
CarGurus has 20,838 nationwide Passat listings starting at $1,800.
Search Volkswagen Passat Questions
Volkswagen Passat Experts