Why did I lose power steering while driving?

My car is a manual transmission, went to turn left so I dropped down to second to turn the corner as I did I realized I couldn't get my car to turn easily (felt very stiff used all my strength to turn the wheel) I did manage to turn the corner and make it to the side of the road, where I immediately put the car in neutral and turned it off. Turned it back on maybe 30 seconds later was only a half a block away from home and wanted to make it to my driveway. Turned into my driveway no problem. Very worried It'll happen again and maybe next time I won't be so lucky. Checked power steering fluid immediately - it's full. Also checked the shield/guard that protects the belt - it's also intact. Also since that's happened I haven't driven much (too scared) but when I do I notice now that my car seems to either idle really high or so low that it wants to stall, don't know if this is connected with what happened to my power steering.