What a challenge!
Remove the spark plugs and squirt a bit of oil into each cylinder. The spark plugs are at the bottom of wells so clean any dirt from the wells before removing the spark plug, dirt in the cylinders won't help.
This engine can be turned by hand - with a 27 mm socket onto the bolt on the crankshaft pulley. You can also try to turn it by putting a wrench onto the nut of the power steering pulley and using the drive belts to turn it. The project is viable if the motor can be turned by hand, otherwise you've probably wasted your money and should consider selling the car as parts.
If the engine turns, drain the oil and add new oil. It will need spark and fuel to run. Spark means the entire ignition system must work - from the key to the spark plugs. You must check each part if it doesn't start.
If this were my project I would CAREFULLY try to test run the engine by trying to start it using propane rather than gasoline. This approach by-passes the whole fuel system and any problems that system may have so you can first determine if the engine runs - or not - before investing time and money in the fuel system. As I wrote, BE CAREFUL for propane is a fuel and can burn you very badly if the engine back fires through its air intake while you are standing there feeding in propane. Work outside, not in a garage.
If the engine runs on propane you should then deal with the fuel system. Gasoline gets stale, after nine years it's useless so drain the fuel tank and do so so that the tank drain hole is at the bottom so any water is also drained. Add a small amount of fresh fuel and fuel system cleaner to help dissolve old fuel deposits.
You will probably need some new ignition parts as well as fuel system parts. This is where a professional M-B mechanic may be cheaper than you stumbling from one thing to another. But the engine should be running - even if badly - before you take it to a professional M-B mechanic.
Finally, you didn't mention the transmission. It too should work somewhat if this car is to be on the road again, otherwise the project is probably not economic. Automatic transmissions depend on clean oil to operate well, old thick oil will not let an automatic work well.
Above all, you should always remember that this old car is just an old junk and you should never risk your safety for it. The only thing you KNOW about it is that someone gave up on it nine years ago. Don't risk having it fall on you and don't risk driving it until an experienced M-B mechanic has checked the steering, brakes and the car's structure to ensure it doesn't fall apart on the highway. Your life is eversomuch more valuable than this old junk box, so with that somber warning start your project.