it may require pulling the toilet and snaking out that sewer line...only thing I can think of preventing flush is it plugged up somewhere down stream..if you believe the toilet itself is not clogged. a few good pumps with a plunger should clear that one..if just excess paper.
if it on the backside of another toilet...they probably share a common vent pipe....so if the other is flushing well...oh wait that means they are tied into the same point on the sewer line too. the only cause then is the toilet is still clogged. give more data and maybe someone can help