Hello,
The only quick fix that you could try is to guide the glass up with your hand to "help" the glass up. Sometimes even when the scissor type regulator is partially disengaged it will hold the bottom of the glass in place. This would be the only quick type of fix.
The only real fix for this is to replace the failing regulator. This is held by rivets and they need to be drilled out so it would be better to have the dealer perform the replacement and to lube the tracks.
This is what it looks like inside the door so you get an idea of what is going on.
Hopefully the help trick works, otherwise replacement will most likely be needed. Please accept, good luck, and thank you.
BMW Mechanic
Level 1 BMW Master Certification, 9 Years Dealer experience, Team Leader, Shop Foreman