I have a folder with several image files. I am able to preview them fine, but I am not able to edit them. I tried to open one with a program such as Paint, but I was told that I don't have permission. So I tried dragging that file to the desktop and tried opening it there, but then it said that it's open in another program, but that wasn't true. Now for some reason, I can't even preview the image any more. This happened to another one already, and it doesn't make any sense. Why is this happening, and how can I fix this?
This sounds like ransomware. You will need to run a boot scan with a several programs to ensure removal. You will need to act FAST. unfortunately encrypted files are virutally impossible to recover. Your best bet is to take your PC down to your local computer repair and have them remove the ransomware for you.
The only other possibility is a slowly dying storage device especially on flash storage.