Irreversible Extents

I clicked Update and security, but what do you mean "The right side of the screen"? Because I dont see much there. Also, I used to use the DotPDN version of Paint.net, but the computer crashed because it ran out of storage space. So we had someone use their magical skills to retrieve the important files and do CPR on the computer to bring it back to life. then I went to download the DotPDN version again, and it said my computer doesn't support it.

SO I bought the program and everything, takes me to windows store, but it says I need to upgrade to the latest version of windows, when Im pretty sure I am at the latest version. No idea what to do.