There are several do it yourself post on that. Try searching window regulator diy.
But a simple version is as follows.
(If you have the HK sound system in your car keep up with the speaker wire when removing the door panel, I didnt mention that part in the how to of this, Mine has it but most dont)
Pull the caps off the bottom of the arm rest to expose the 2 screws on the bottom of the armrest. Pull those out with a T20 torx screw driver. Then pull the window switch out of the top of the armrest with a flat blade screw driver carefully. You will see another T20 torx screw down in the hole the switch came out of. Remove that.
Gentley pry the wood trim piece out from the outside of the door aka that side that is open. It tucks up under the handle side is the reason you have to do it that way. Pull the screws out of the door panel that were behind that trim piece.
Pull the door panel off starting at the bottom of the panel using a paint scraper or a long flat screw driver. The bigger the item you use to remove the panel with the less the paint damage to the door. So you want the widest flat item you have to do it.
After this it lifts straight up kinda. Once the panel is pulled out a little bit look down between the panel and the door itself and notice the door handle has a cable going into it. There is a white clip that rocks outward to release that. Be gentle with it. Unplug the window switch you pried out ealier and poke the wire back thru the panel. Now the panel can be put aside.
Next remove the molded insert from the door itself. It looks like sound deadening matt stuff. Paint scraper is best. Try not to damage it
Now your looking at the regulator. I think its 10mm bolts that hold that to the door. But first get the window down far enough to see the bolt that attaches the regulator to the glass. Remove it and catch the nut that might fall of the back side when you pull that bolt out. It isnt suposed to fall out but sometimes does.
Next pull the glass all the way back up to the close position by hand and pin it there or have someone hold it. It doesnt take any real effort to keep the glass up a small child will do
Next pull the bolts out of the regulator itself. You wont have any problem seeing which is which if you have the new regulator to look at. Once its out some unplug the motor wire and then pull the screws out that hold the motor to the regulator. Now put the motor onto the new regulator. Plug up the motor. Put the new regulator back in the door. Bolt it in place but do not tighten the bolts completely yet. Now use the power switch (plug it back in for now) to put the regulator in a position to allow you to re-attache the glass. Lower the glass to that position and put the bolt back in that holds the glass in place. Now run the window all the way up and down a few times. Then with it up tighten the regulator fully to the door. Unplug the switch again to keep it out of the way. Now put the sound material back on making sure the door handle cable and the power window switch wires are not caught behind the sound proof stuff. After that get the door panel in place and hook up the handle and poke the wire thru the door panel for the window switch and put the switch on but of course dont put the switch back in its place yet
Starting at the top push the door panel back to the door clicking all the prongs back in place. Once thats done put the screws back in the part thats going to behind the wood trim piece. Then pop the wood trim piece back in place by tucking its tab behind the door handle first then working outward. Next put the screw back in the hole where the window switch goes. Then put the window switch back in place. Then put the screws back in the bottom of the armrest. Then put the tabs back in place that cover those screws.
Get some windex and clean all those greasy finger prints off the glass.
Welcome to Bimmerfest , seeing that this is your first post.
In the future however, you should learn to use the search feature because this question has been asked and answered a ka-gillion times.
A good place to start BEFORE you post whenever you are looking for answers is the WIKI. Refer to the sticky at the top of this sub-forum. You will find references to the most common problems with our cars. This is much faster than waiting for a response as there is often no hurry to answer a question that is asked all the time.
Anyway, this is a link to that section of the WIKI.
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