It can be opened with winrar or 7zip, you mean that even after unzipping it it doesn't work? @@
(I'm looking at a way to fix it too atm, it neve happened to me before ;__;)
So, I found this solution, it's nothing damaging to the computer, maybe it might be useful!
Let me know how it goes ;w; https://www.tenforums.com/general-support/126563-rar-files-opening-notepad.html