If you save your ini file with UTF-16LE with BOM encoding, it handles Turkish characters.
#include <Constants.au3>
#include <Debug.au3>
example()
Func example()
Local $aIniSection
$aIniSection = IniReadSection("test.ini", "Türkçe")
If @error Then Exit MsgBox($MB_ICONERROR + $MB_TOPMOST, "ERROR", "IniReadSection failed - @error = " & @error)
_DebugArrayDisplay($aIniSection, "Türkçe Section")
MsgBox($MB_ICONINFORMATION + $MB_TOPMOST, "Türkçe", "Key = " & IniRead("test.ini", "Türkçe", "Key", "Not Found"))
EndFunc