Fans have been asking this since the end of the Last Stand. After being disintegrated by Dark Phoenix, Xavier apparently survived by transferring his consciousness into the body of a coma patient in the care of his long time friend Dr Moira McTaggart. We say apparently because he appeared in his own body, alive and well (yet somehow still in a wheelchair) at the end of the Wolverine and at the beginning of DOFP. Nobody seemed at all surprised to see the Professor still among the living. Bryan Singer may have sneakily used time travel to undo Xavier's death in the Last Stand, but that doesn't explain how he was alive before Wolverine went back and changed history. We get that Singer was determined to ignore Brett Ratners movie (like the rest of us) but you can't just pick and choose what happened and what didn't!