I cant get over the death of my mom....?

My mother died 4 years ago and i still cant cope with it. i always push it to the back of my head and try not to think about it. i was a typical Mommy's boy.. i am now 22. i have always blamed myself thinking if i was at home i could of saved her. it was a very sudden death no one knew she was ill apart from her. when i lost her i took overdose's of anything i could i was put on tablets by the Doctor and made to speak to councillors but i left all that and that's when i pushed it to the back of my head. i feel like everyday its eating away at me and i don't know what to do......