Which version of Acrobat are you running? Does it prompt you to recover an unsaved document when you try to start it up again? If so, just let it recover the document and you should have (almost) all your comments in the recovery document. Save this document and remember to save every few minutes from now on. If Acrobat cannot recover the document then unfortunately your comments are lost.
Thanks for replying. I'm using Adobe Acrobat Reader DC with Windows 10. Unfortunately, I was working for many hours, and I don't think I did save it before my computer crashed, although I did see the prompt and said yes, yet then my wireless went out.