FAQ: Make Notepad++ x64 "Open with..." menu work in Win7
Since Microsoft ended mainstream support for Windows 7 in January 2015, this issue won’t be fixed in Notepad++ installer.
However, you can fix manually if you use Notepad++ x64 under Windows 7:
The registry values had to be updated. I actually did the inverse of Gusgus01's referenced issue above since I have x64 version installed: Pop open regedit > search for ""C:\Program Files (x86)\Notepad++\notepad++.exe" and replace with the updated x64 directory "C:\Program Files\Notepad++\notepad++.exe." Now the 64bit Notepad++ programs appears in "Open With" > "Choose a default program" > "Recommended Programs."
The link of the whole post is here: