There are 6 screws total that you need to remove in order to open the case (bottom and both sides, each has 2 screws)
Carefully remove the screws using a screwdriver and put them somewhere safe so they will not get lost.
Open the case gently. The wrist strap plate and disk pieces will fall out during the process. The second picture shows what wrist strap plate and disk looks like (The circled parts).
Replace the broken camera case with the new one.