Help with dry, knotty, and frizzy hair!?

ahh help please! My hair seems like its always dry and knotty! and lately its been frizzy too! i got my hair cut the other day at a salon, and everytime iget it cut my hair is amazingly soft, unknotty, and nt frizzy! and it was perfect for like 1 day! and i asked my hair dresser for the shampoo and conidioner so i could keep the soft hair, and i washed it 2 times in like 4 days and its incredible dry and knotty! my friends hair is so soft and light and mine is all dull and gross! i feel like i just dont know what to do with it anymore! pleaseeee advice!!!