The default method of opening unknown files forces you to go through a list of known applications and is generally a pain to deal with. That’s why I like to have a context menu option for “Open with Notepad” so that I can quickly open up files without having to go through a lot of trouble.
So see what You have to do>>>>>>>>>
There is a simple registry hack Manual Registry Hack
Open regedit.exe through the start menu search or run box, and then browse down to the following key:
HKEY_CLASSES_ROOT\*\shell
Right-click on “shell” and choose to create a new key, calling it “Open with Notepad”. Create a new key below that one called “command”. Double-click on the (Default) value in the right-hand pane and enter in the following:
notepad.exe %1
The change should take effect immediately… just right-click on any file and you’ll see the next menu entry.
OR
If You are Confused then Watch This Video