Hi Paul-Émile, I am Paulo. I'm an Independent Advisor.
Try using the search box in the start menu instead and enter the command %appdata% there or simply use Win + Run then just type Appdata without % and see f that opens the folder.
If that still won't open the Appdata folder, try the solutions in this thread:
https://answers.microsoft.com/en-us/insider/for...
https://answers.microsoft.com/en-us/windows/for...
I hope this helps with your concern.