SmackDown85

My passenger side rear window is saggy. I walked out to my car from work one day and noticed as I was driving down the road that my rear window was down. I tried to roll it up but nothing. When I pulled over to check it out it would not roll up at all, so I was forced to manually pull it up. Then I found out it wouldn't stay up. Any ideas what the problem is and how I can fix it? Is it worth fixing it myself or should I take it somewhere? Thanks guys, as always.