Is that actually a crack? In the shot I can see something that looks closer to snap/locking tabs and don't see a typical plastics fracture surface, to that end it well have popped out when it got booted and a bit of pressure could get it back in.
That said one of the possible snap tabs might be broken so there is that.
I did try watching a screen replacement video but they were more interested in replacing the screen than showing detail for the hinges, and a generally disassembly did nothing either.
Finding replacement plastics can be a pain. It would probably fall under the term bezel if you wanted to search the likes of ebay, though hinge covers is another option. I am far too lazy right now to hunt down an official parts list/manual. Alternatively if someone is selling one as a parts laptop (no ram, battery, hdd, no working screen...) you might find it on there.
If that is tricky then we can talk about plastics repair methods, none are particularly great though.
