Passenger power window goes down, but not up!

[losername]

i have a '91 mustang and i recently rolled down the passenger window about half way only to find that it wouldn't go back up... but it will still roll down .

the drivers side window is still working fine. anyways, it's -35°C outside and i freeze when i drive so any help would be sweet. oh, and i'm a poor college student so any do-it-yourself suggestions would be nice