Change png files back to default.

Help, please. Every file on each folder of my computer, all my PNG, and other files in my downloads have somehow been converted to notebook files. How do I change them back?

I would try Bulk rename utility and change all the extensions from .txt or whatever the extension is, to .png if that's all that happened first time round. If they were actually somehow converted however, doing this would corrupt the file probably, if not, it should be fine.

right click and open with > choose a paint app and set always instead of just once

Thanks for the replies, but it didn't work. I hate computers sometimes.

are you sure you dont get a cryptolocker ?

in the view tab, click to unhide file extensions, they should still say .png, I think you have set a bad file association