Hi, thank you for contacting JustAnswer.com. My name is***** will do my best to provide the right answer to your question.
A 'hard shutdown' sounds like several different things to me. Please describe a few points about it:
- did the screen go black?
- did the cooling fan shut off, before it went black?
- If the cooling fan had failed, then the CPU may have invoked its overheating protections, and shut the computer Off. (This happens when CPU chip cooling has failed... e.g. with cooling fan lockup or other cooling fan failure. It heats up very quickly, there's no time for warnings, etc. It turns Off to avoid burnout of the CPU chip.)
If so, then the unsaved data is lost. It's always good to save your work often, even if we are not living in the age of mainframe dumb terminals any more (when it was an almost required thing to do.)
I don't think the hard disk is damaged. Probably not.
But if the above is all correct, you'll need a repair shop for the fan.