abc resevoir is empty and i heard a loud air or hydraulic explosion on the left rear.

Hello, could you have heard an air suspension noise perhaps? Is there a physical change in your vehicle's ride height? I'll be honest, this concern isn't really much for the "do it yourself" mechanic; you really need to seek a skilled, experienced Mercedes-Benz trained professional. Use this link to find some shops near you that can help with your concern: www.repairpal.com/repair-shops