Does not support on sinhala Unicode correctly. plz help!

dos not support sum impotent fonts only. so can’t use with ‘sinhala’ language

You have to set up your operating system. You need a suitable Unicode font and a keyboard driver. That is not the task of LibreOffice. You might find what you need on Local Languages Initiative | ශ්‍රී ලංකා තොරතුරු හා සන්නිවේදන තාක්ෂණ නියෝජිතායතනය - ICTA. It has a read button “FONTS” and a read button “KEYBOARD INPUT & ETC”.