How to fix: Can’t see Unicode (UTF8) in Notepad++ on Windows XP
This is a little late to help most people because they have moved on from Windows XP to newer flavors, however there are still some die-hards going to 2019 with the simple PosReady registry tweak.
If you have a full unicode font installed like Symbola on Windows XP, you may still not see proper characters in applications like Notepad++ and instead get double empty boxes in their place.
The reason for this is despite any character/language enabling from the control panel, there is still a critical registry setting missing.
Found the answer here: http://www.i18nguy.com/surrogates.html
Enable support for Unicode supplementary characters (surrogate code points)
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\LanguagePack] SURROGATE=(REG_DWORD)0x00000002
Add that via regedit, be sure to reboot, and it will magically start to work in Notepad++