It may be that the awning fabric slipped off square either at the awning rail on the trailer sidewall or on the roller tube. Unroll the awning, and watch as it rolls back up. It should roll evenly, if it does, then most likely the awning arms are bent or misaligned. If, however, it rolls up toward one side or the other, you can remove the screws from the awning rail (at each end of the fabric) and pull the fabric one way or the other to square it so that it rolls up evenly on the roller tube.
If it's the awning arms, then look closely for a bent connection screw, a twisted arm component or a "tweeked" attachment fitting on the trailer sidewall.
Hope you get it repaired