I was reading about the fall of Constantinople recently, and I think it mentioned somewhere that the Pope was unable to rally support for the defense of the city due to most countries being in a weakened economic state or too wary of the Pope's growing power. Would calling a tenth Crusade have been a viable option?
They did try to organize crusades before and after the fall of Constantinople, but there wasn't much enthusiasm for it. Sometimes things like the Battle of Lepanto in 1571 or the Sieges of Vienna are called "crusades", but there wasn't anything like a specific military expedition against Constantinople (or Jerusalem). By then, they had lost interest in crusading, which pretty much always turned out to be an expensive waste of time.
Lots more can be said about this, but here are a couple of previous answers I wrote that might be helpful:
Why were there no more crusades after Lord Edward's ? (in 1271-72)