My case fan all of a sudden got REALLY LOUD!!

[BlackScarletLove]

It just started rattling and grinding and sounding terrible. It's the case fan on the back, not the side, not the power supply or the psu, I know this because I reached in and put my finger in the fan on the back, stopping it, and it was what was causing the noise.
It was so loud that I actually inhibited the fan so it's not working now. My case is open so I figured it wouldn't get too hot in there, but what can I do to fix the fan?
Blowing it out with an air can didn't do any good.

 

[LordOfLA]

buy a new one. The bearings are gone 🙂

 

[Admiral Michael]

Don't stop the fan by putting something in the way, you should unplug it.

 

[BlackScarletLove]

Don't stop the fan by putting something in the way, you should unplug it.

what happens when i simply obstruct it? 😱 is it dangerous?

 

[Admiral Michael]

It may overheat, it may do nothing. Hard to say but I myself would rather be safe then sorry.