My (optiarc DVD RW AD-7703S) which came with my new toshiba satellite a665 series..doesnt read dvd's?

i bought a new laptop (satellite A665 series) but unlucky to find its dvd rw not working after 3months..the main problem is whn i insert a dvd it doesnt giv any response while vcd are read..but none of them can b written..i.e i cant copy vcd n dvd..my laptop was bought in san francisco.. 1st it was gud but wat would hav happened in just 3 months.