Right LCD Screen Assembly hinge lock broken after drop

The part you highlighted is attached to a large frame thing inside the display assembly. You can access and replace this frame, but you will have to remove the glass and the LCD panel first, which is quite a time consuming repair (MacBook Pro 13" Unibody Mid 2010 LCD Replacement). Then, you can take out the screws that hold the frame in place, heat the adhesive and the frame will separate from the back cover. I don't know of any sources that sell just the frame, so you will probably have to salvage it from another LCD assembly.

It's most likely the best for you to just buy a whole display assembly and replace the broken one with it. (Sostituzione schermo MacBook Pro 13" Unibody metà 2012)