Frame has come apart from mirror

Hello, I'm hoping to fix my closet. It's has been struggling on the tracks for quite some time and now the mirror has become disconnected at the top of the side and I can't figure out how to get it back together. I may need a new track so I can get this in better operational shape. It's the 71" track. I can't find any loose parts on the ground so I'm not sure what the problem is. Please help! Thank you,
-Erin