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I had a file that Windows did not recognize. It was called
abc.per. This is the correct extension for the file. The file does not open in any known Windows programs either (this is also not a problem). For some reason, I changed the file to always open with Notepad.
Now I want to get rid of the fact that it always needs to open with Notepad, but Windows just doesn't allow me to get rid of this behaviour. I tried to rename the file in which case it loses its extension, that is,
How do I remove the extension and restore the default behaviour of the file?
I am on a 64-bit Windows 7 system.