How much does a transmission cost to repair for this car?? on 1999 Volkswagen Passat

3 weeks ago the car started shaking. and in the last week the check engine light came on and the car will no longer move into gears. Does this mean the transmission is completely shot? Also the back seat behind the passenger side gets completely soaked. Do you know what this comes from????

Asked by for the 1999 Volkswagen Passat