You definitely need to post more information. Which fan stopped working? You could just take it to a shop, laptops aren't as easy as desktops to take apart and I don't know how much experience you have with that.
Try and look at your fans and see which one stopped working. If you see a fan with a copper pipe attached, it's the 2nd one. If it's a single fan, the first. Just replacing your fan might not fix it either.
Can you post the exact message that comes up? I'm kind of leaning towards the 2nd fan but it's a shot in the dark.