Once you get the tailgate open, you'll need to replace the latch assembly. The plastic pieces you are seeing came from the plastic cover molder over the catch. This plastic part provides an attachment point for a small spring that assists in the proper function of the catch. The plastic can break when the tailgate is shut too hard. I bought a complete latch assembly from Erie Volvo for $65 earlier this year. This is a DIY project if you are willing to try it. There are a number of linkages attached to the latch mechanism and I suggest you make a sketch or take a picture of how it all goes together. I know from experience, it took me a few tries to get it all working correctly after I installed the replacement latch. Good Luck!