I found it a little rambly, making me want to skim and a little telly rather than showy... but you just want grammar corrections, so that's what I'll give you.
Reyu wrote:My name is Jack smith.
Should be 'Smith'.
Reyu wrote:The dead only knows death.
Firstly, it should be 'The dead only know death.' And secondly, I think that since this is a reoccurring theme, you should make it flow better... maybe 'Only the dead know death.'
Reyu wrote:My only hopes is that whoever may still exist have not gone completely mad.
Should be 'hope' not 'hopes'.
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I think that's it for the grammar... you could work on it to flow better, though...