Problem: The scuff plate is held in place by a screw. The thing is the screw is screwed into some threads below the scuff plate. I think the screw threads are glued onto the car, and somehow they fell off, into the car. Can't get to them and I do not know what to use to replace them. Anybody has any ideas?

 

I think you are talking about the aluminum dealer accessory scuff plates? If so each plate has 2 holes drilled into the rocker panel of the car and a small rubber bushins is placedin the hole and it has a lip that keeps it from falling into the car. If you lost one of them you can probably find something cutom at home depot to work. If not, I would just some silicon glue called "GOOP Automotive sealant". This will glue it on and when you need to take it off you can break the seal and just re-seal again. I'd use it as a last resort but it will work.