https://www.bleepingcomputer.com/forums/t/626812/how-do-i-fix-acpisys-is-missing-or-corrupted/

May or may not be connected. Do you have another machine that can access the old one so that you, or someone, can get off any information.

I guess it depends on what you want to achieve. If the machine has important stuff on I don’t think that reinstalling will do anything apart from lose your data.

I guess it also depends on how comfortable you are troubleshooting computer problems. And also whether you have a back up of anything of importance. If you have then getting it working again may be the priority.