hey i need some help i killed andre and now i cant +10 my Great Scythe i wanted to see if anyone could help me thank you =]

You might have to beat the game, then do it in NG+. You should check the dark souls wikidot page though to see if any other blacksmith can, the giant blacksmith in anor londo may be able to do it.

what platform?

youre pretty much fucked

I still play this game I don't seem to get tired of it. If you killed the blacksmith Andre you can no longer +10 weapons or armor until your next play though but you can still upgrade weapons there are lots of weapons and armor that can’t be +10(for example the stone great sword) so just play that game using them until new game plus. I myself killed Andre by accident the first time I played and it did not hinder my game play. even if you kill all the black 3 killable black smiths in game you can still upgrade gear yourself or using the none killable blacksmith in a cage (Rickert of Vinheim Off the side of a dead-end stair in the beginning of New Londo Ruins, in a cage)