Fan not spinning automatically, spins on manual push, laptop overheating (HP Probook 6450b on Windows 10)

I have an HP Probook 6450b Laptop that gets hot. I tried replacing the thermal paste, but it's still very hot. Then, I left for almost a year. Some days ago, I picked it up and then tried a new thermal paste; I discovered that the thermal seemed to work this time. I also found that my fan is not spinning. It won't spin until I give it a push. It will also spin during boot and stop after boot. Or stops after a while. I have cleaned it. But it's still not working. Please, what else should I do? The laptop runs on Windows 10.

Question by Viraaltech on Super User, licensed CC BY-SA. We show a short excerpt and link to the original thread as credit.