I don't think the timing chain stretch will prevent your car from starting. It might put your timing a little off, though.
You probably have other problems.
How long has it been since the timing chain and upper rails were replaced anyway?
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".