File system corruption caused by unexpected power loss or hardware issues

I recently experienced an unexpected power outage while my PC was running, and now I'm seeing file system errors, random application crashes, and some files won't open at all. I've already run CHKDSK and it found several corrupted index entries, but I'm not sure if that fully resolved the issue or if there's underlying hardware damage like a failing hard drive or loose cable, so I'd really appreciate any guidance on how to properly diagnose and repair the file system corruption without losing my important data.