|Need more information.|
System specs, recent history of problems, what you have tried, are we talking about a desktop or laptop, if desktop are you talking about CPU fan, Case fan, or Power Supply fan, etc.....
Is the computer otherwise running without the fan?
If running, install HWMonitor and see what your temperatures are and post them all. (If running, catch it..... Ha ha)
You may simple need to replace a bad fan, but without more information, no one could tell for sure.
You have to be a little bit crazy to keep you from going insane.