On your model of MB it's very important to replace the timing chain and guides every 10 years or 100,000 miles. The chain guides begin to get very brittle and if they shatter they will do major damage to the valves. The chain will likely jump time and bend the valves, requiring a major top end rebuild.

If the chain and guides have never been replaced your vehicle is well overdue. Certainly do not start the vehicle until you have done this service, because if the guide broke without causing any other damage you are unbelievably lucky. It's not extremely difficult to replace the chain and guides, it just requires some time and know-how. Good luck.