404 not found error

Take a look here:
https://codex.www.ads-software.com/Moving_WordPress#When_Your_Domain_Name_or_URLs_Change

Thanks so much. I did look at that but am such a novice that I can’t quite understand whether what I’ve done is irreversible or if I can do the search and replace thing and get it back to normal.

Nothing short of deleting is irreversible. Search and replace should get you back on track.

OK! Thank you so much. I have one more question. The instructions on the search and replace script say to install root folder of my wordpress install, but I can’t access my wordpress account without getting that 404 error. And i’m not sure where the root folder would be even if I could access it.

Any ideas?

Thanks again for your help. I was able to get this resolved through my hosting company. (Thank goodness!)