First: get yourself a real knife block. Tossing all your knives loose into a drawer is ruining the edges, and keeps them duller than dirt. A dull knife is dangerous.
Second: I wouldn’t bother trying to fix that. The particle board looks like humidity has done a number on it, and it’s falling apart. I would suggest getting a new drawer made out of 1/2" plywood (1/4" bottom) and box joints. It’s pretty easy to do if you have a table saw, but if you’re asking here, I’m going to assume you don’t.