What happens if my player character is resurrected(?) by a Necromancer? [closed]

My player character was killed off by the DM, my party found pieces of my body in a room.

They’ve taken my head back to the Necromancer we met.

My questions are:

What can a Necromancer do? Is it just resurrection or can they do revive? Or something else?

If I’m resurrected, doesn’t this make me undead? And if so, doesn’t that mean I wouldn’t have a need for Hit Points?