How do i open up my brain cells once i destroyed them years though with drugs. my memory is awful, i almost feel brain dead.

Can't open up: Yikes! 20yo? Sorry for bad news but you can't "open up [your] brain cells" but you can improve your memory & clarity of thinking by stopping use of illicit drugs (and improper use of prescription meds, too). Good nutrition & regular exercise will go a long way towards improving your health & brain function. If ok w/religion & culture, check out mediterranean diet. Lots of evidence that it's good.