Hi Taffy
OHhhhhhhh I know that sound so well!!!
What has happened, in short your window riser cable has jumped tracks inside the motor when you wound the window down the other cable has rolled over the jumped cable and trapped it causing it to be put under a load of tension, which then due to the pull snaps the plastic slot which holsa the cable to the window riser, th bang you heard was the metal nipple on the end of the cable hitting the car bodywork inside the rear wing. both winding wheel and cables are dead now, the wheel becasue the plastic track slots are compromised and can't really be cleaned up again and the cables becasue they will be badly kinked so will never run true again.
to remove the regulator:
viewtopic.php?f=25&t=10467you can buy a used reg from scrap yard or ebay, search for breaking Meg CC as they very rare list these parts and ask the question, they very rare advertise this part. Some one on here has had one repaired of some guy on ebay, doesn't help you really as the car will have no window in it. or of course a new one. both will come with no glass.
Temp Fix.....
follow the above link to remove the regulator, when it is on the floor you will see it is all on a backing plate, this paragraph will become clear when you see the complete unit, next you need to get rid of the cables by either removing the motor head (3 torx/philps bolts depending on motor) take off the cover and remove the winding wheel and cables or cut them and pull them out, this might be very hard depending on how well they are jamed but they need to be out, once free replace cover as you need this motor to be working freely, now push the window up to the top of its travel (shut postion) secure with two bolts, one in each window travel slot right under the glass mount, I used 2 nuts n bolts and 4 washers for mine, once tightend the glass will not be able to be pushed down.
replace unti back into car, plug in motor (I did not do this initially and my roof would not work) lift roof on, you will need to adjust the glass now (you would have to do this even with the new/used unit) remove the large rubber gromets on the inner panel inside you will see 1 10mm bolt in each these adjust the glass height, further down where the motor is you will see the 10mm sliding mount you will have had t oundo this one to get the unit out this one adjusts the glass lean, eithier outwars or inwards yo uneed this glass to be touching the rubber seal have a look at the other side for correct postion, you also need you front door closed to get it t oseal on that aswell, bit fiddly and time consuming this bit but worth that extra effort, stops water coming in. once you are happy try the roof on and off a few times watching carefully how it interacts with this glass now it should fit nicely on to the glass. when happy.
take roof off and replace the rest of your bits, car now looks good and is secure from the weather and any moron passing, I did mine 2 years ago after two regs on the same side went, and is still bolted up to date and working a treat, even if you manage to get it up and tape it there is a definate possibility you can push it down. at the end of the day bolts are cheap and the car safe whilst still able to use the roof all other windows will still work and it gives you thinking time, will have a look at my reg in the garage tonight and get its slot sizes for you, the job is not as bad as it sounds takes around 2 hours.
Hope this is ok.