Knowing what model and year of vehicle that you have would help.
Let us know based on the first few letters of the VIN i.e. W210 model (E class 1994 -1999 ish). VIN usually starts WDB210 for saloon and SDB210 for estate, if memory serves me right.
A common cause of rear window failures on W210 and W211 vehicles is caused by the window regulator breaking. It's the mechanical linkages used to lift the window. It is possible to replace these and there is a DIY thread covering it.
If you let us know what the model is then I imagine that Malcolm can post a link to an exploded layout picture. I would imagine that mode MB vehicles use similar mechanisms to actuate the windows, but you'll need to use your judgement on that.