This is a very easy process as you will have to go to Windows Notepad app and type these:
RepositoryFolders=TextFX Original:%CSIDLX_TEXTFXDATA%\ReplaceSets;Most Recent
...and you will just have to save it as "NPPTextFX.ini"
Some plugins have issues with NPP.
You must deactivate all plugins by moving their .dll files from folder "plugins" to "../plugins/disabled", then move them back one by one to reactivate it. After you activate one, try to launch NPP before going on.
This solved my problem. In my case, the .dll that was causing the problem was NppExternalLexers.