My left front window has stopped working

[NW_Merc]

As the title says, the front passenger side window has stopped working. Although I do hear a clicking when the switch is pressed coming from the boot. What is the best place to start to fix the problem?

 

[Dec]

You could try post #7 HERE its for a back window but same idea, it will confirm if it is the motor or not.
Removing the door card, See Post #5 this is for back door but again same idea.
The click you hear is the relay and that is normal.

Dec