If you can't find your cover... look at the car to see if there is damage around that cover... Probably a good possibility that someone broke into your car and maybe you got nothing they want.
Yes, dealer has new cover... easy to install but you have to know how to lock it in... on the side of the door, there is a cover.hole in line with the upper part of the cover... shine a flashlight into it... you will see a level where you can push to release and pull to lock that cover in... you need a small hook to operate that level...
With the cover off... as you move the level in and out, you will see at the upper holes that it basically slide a plate into the hole area and away from it.