There are only a few problems typical with our C4 UrS car front doors: a lock starts acting up, the window stops going up or down and wind noise.

The first thing you need to do when you figure out that it is something inside the door, is to remove the door panel. One procedure to do this is shown HERE

If it is a lock problem, this diagram should help (note how the cable hooks to the inner door handle and the door lock mechanism):



audi//s/scott says sometimes the Item 31 clip (above) pops off, rendering the cable useless. (Check)

If it is a window up/down problem it could be the regulator cable or the motor. Here is a diagram to help you to figure out how that works:



If its the cable, either you need Item 1 above or you could try replacing just the cable, as Popdemonic from Thailand detailed HERE

If it "just" wind noise, the upper door/window guide (Item 5 below)may need to be adjusted (using wedges (Item 2 below) as shown in this diagram):