How can I recover macOS Catalina after accidentally erasing internal data in Disk Utility?

So when I launch recovery mode and look at my disk utility after I erased the internal data (I think that’s what I erased). When disk utility is opened I only see the MacOS base system is that normal?

My friend could be wrong but he said I might have deleted the operating system on accident, but we’re not sure. If I did can I restore it?

Note: I have tried to restore MacOS Catalina, but yesterday it switched to High Sierra. High Sierra is worse than Catalina so I’m at a loss.

My attempts to restore MacOS haven’t really worked. Does anyone have any suggestions or next steps I should take in order to resolve this issue?

[Re-Titled by Moderator]