My computer is destroyed

Hello,

my computer started to shutdown by itself so i tried all kinds of antiviruses but none worked it turned all of my security settings off like firewall and norton and it stopped the system restore so i couldnt use it and one day it just shut off and when i turned it back on it just went to the black screen and said something was missing and that i had to restart but when i restarted it, it said the same thing. can someone please help me!