@Hanul-Kim
I can’t remember if this is normal or not and as I currently do not use
a windows operating system I cannot test this.
Do the files open with npp if you double click in explorer?
If yes, everything seems to be ok.
If not, give it a try to register extension by using right-click and check the box open always…
In regards to the 32bit vs. 64bit npp version.
You can use both versions even on a 64 bit Windows 7.
Each version has its advantage and its disadvantage.
Using the 64bit version eliminates the problem with file system redirection
but disadvantage is that, currently, not many plugins are available.
Using the 32bit version on a 64 bit operating system can cause problems
if you want to open files which are available as 32bit and 64bit version.
(https://msdn.microsoft.com/en-us/library/windows/desktop/aa384187(v=vs.85).aspx)
Advantage, many many plugins which enhances npp functionality are available.
So, if you do not use plugins - stay with the 64bit version.
Cheers
Claudia