laptop suddenly powers off

My laptop has been experiencing sudden power offs. I don' t think it turns off completely, because I think my data was still there when I turn it back on. Could this be because of overheating? It's a 4-5 year hold hp pavilion ze2000. Been through a couple reformats. My virus/malware scans didnt pick up anything.

If the laptop is overheating it will shut off completely. This means when you turn it on it will boot fresh and anything you were working on will be gone. If you are saying that when you turn the laptop back on it comes out of standby/hibernation and your computer is just the way you left it, then it is not a heat issue. However, what it does signal is that there is a power problem. At some point, the laptop is losing power and when the battery gets low it goes into standby or hibernation automatically most likely.