Ok my last save was at the start of the dawnguard quest line >.< not doing it all again my last auto-save is right after its finished i told Serena i didn't need her on my adventures as i thought it meant she would go back to Dawnguard keep.

I WAS WRONG.

I tried player.placeatme it made a version of her that just said hi etc i tried player.placeat that didn't work i wan't to know how to get her back as i want to marry her :S