Negatives in the simple present are formed by adding don't or doesn't before the simple form of the verb:
do, does, don't හා doesn't යන පද වර්ථමානයේ යෙදේ.
In other words, only THIRD PERSON SINGULAR subjects (he, she and it) have DOESN'T -- the rest have DON'T.
අන්ය පුරුෂ ඔහු, ඇය හා එය සඳහා භාවිතා වන්නේ DOESN'T ය