as you said you do not brush your teeth and now these are yellowish and your gums are bleeding. this problem because of poor oral hygiene
.because of poor oral hygiene food got accumulated over teeth and gums and this destroyed teeth and supporting structures like gums and bone and ligament. now i will suggest you please go to a dentist
as soon as possible and go for complete examination done.go for scaling and please follow all the given instructions properly.nothing to get worried.but tale an immediate action for your teeth,other wise you can loose your teeth.