I have a low functioning brain

Im so tired of being like this , I wish knew how to act normal , Everyday I make at least 3 mistakes , at work or at life , Im so awkward and I dont feel exactly sober ? Like , I cant even think with clarity at times , and I end up making poor decisions for me and people I wanted to help . I feel like I want to only sleep even if i dont even work hard . How do i make it get better ?