Can't delete or take a screenshot

Hi!

I have a MacBook Pro from 2020.

When I try to remove a screenshot from my Mac by moving it to trash, it asks me for my finger-print or password to allow this. This is unusual, as it normally does it straight away. After I give the mac this information, it tells me that it cannot complete the action because I do not have access to some of the files.

Next, when I take a screenshot, it appears to work at first. However, when I go to look for the screenshot, it's like it was never taken (no matter how many times I take the screenshot).

Could somebody please help with this?

Thank you!