Solution For Blank Squares in Taskbar, Task Manager etc. (NOT FOR DESKTOP ICONS- FOR DESKTOP ICONS RELATED YOU HAVE TO REBUILD ICON CACHE)
Boot a Live OS, Copy All the Segoe Fonts from C:\Windows\Fonts and then copy it to C:\Users"YOUR USERNAME HERE"\APPDATA\LOCAL\MICROSOFT\WINDOWS\FONTS and Problem Solved. The versions of those fonts will be different.
TRUST ME YOU CANNOT COPY THESE FONTS WHILE USING WINDOWS AS IT WILL SHOW AN ERROR STATING FILE IN USE.
SO LIVE OS (Use Lubuntu or any linux or second os/ OR CONNECT YOUR HARD DISK TO ANOTHER PC TO DO COPY/ OR USE CMD IN RECOVERY MODE TO COPY- ADVANCED) IS BEST UNLESS YOU ARE A NERD AND YOU GOT PLENTY OF TIME.
Kudos,
UX Stalin
:)