Your tooth discoloration
is due to external stains.
High intake of coffee & Tea, Spicy foods,Betel nut chewing, smoking,are reasons fir external stains.
Kindly visit a dentist
, he will do the scaling & polishing.If necessary undergo bleaching
which will make ur teeth look brighter.
Brown color Gums are due to excessive melanin pigmentation
(as d previous dr said).A small clinical procedure will solve the problem.Nowadays Lasers are used in depigmentation procedures.
Ask ur dentist abt it.