OK here is how to un-associate a file extension to unknown . . . Right click your Desktop, choose 'New' - Text Document When the document opens, you need to save the document with a .bat file extension Click File - Save As At the bottom of the save as dialog, change 'Save as Type' to 'All Files' Manually enter the file name XXX.bat Now right click any file you want to disassociate and choose 'Open with' - 'Choose another app' -' More Apps' Check the box marked 'Always use this app' Scroll to the bottom and click 'Look for another app on this PC' Navigate to the XXX.bat on your Desktop and select that Finally delete XXX.bat from your Desktop and restart your system The file association will be reset to unknown . . .