After running over a stick and getting it caught both in the chain AND between by cassette and rear der., the cage was sticking into my rear wheel spokes. I stopped to assess the damage and my rear der. was UPSIDE DOWN. I haven't ever seen this, but after I wiggled the stick loose, I had to loosen the der. bolt to get it to swing back into normal position. As I did this, the B-tension screw, along with the screw's housing, I guess I would call it, went missing from the rear der. I tried to ride again, but the der. cable had been ripped out and the der. was bumping my cassette as if I had no B-tension, because it didn't have any and the screw and however it attaches to the rear der was gone. Does this sound like a Tales from the Crypt episode where I'll be ponying up for a new der. or will I be able to salvage this one and ride again soon? Thanks for any help.