Steering Problem

Ok well I was driving all night today and everything was fine untill i got in my car after eating and my steering was really hard to turn like I lost all my power steering. So i checked the power steering canister thing and the level is good, so I’am thinking no leaks what else could be wrong to cause this?

Please let me know, Thanks!

check p/s belt ,pulley, could also be actual p/s pump and have seen the steering knuckle joint start to seize -soak in WD40