I can't open .kra files and edit them. How do I fix this?

Start by giving us some information.

* Which version of Krita are you using, give us the exact filename of the installer, zip, appimage or dmg you downloaded.
* Which OS are you running
* Does this happen to all .kra files or only some files?
* Does Krita give you an error message when loading the file?
* Does this also happen if you create another user on your computer and test Krita as that user?
* If on windows, does the file explorer show you a thumbnail if you have used the installer, or installed the shell extension separately