Last evening as I was turning the corner if.

Last evening as I was turning the corner if front of my apartment the passeger side window drop downed to about half way. I pulled up in front of the apartment and got out and looked and I could raise and lower the window glass by hand but it wouldn't stay in any one position. They were calling for heavy snow mixed with sleet and I didn't want to leave the window open at any height so I managed to wedge in place. Do you have any ideas as to what happened and how easily can this be fixed? As I said it's a 1998 Nissan Sentra Xe with 300000 miles on it and I don't want o spend any great deal of money on it at this stage. Any suggestions?