1

possession (your spirit has taken over the body of another person in another world, relax, their spirit probably moved on to a higher plane or something, you're not a demon or anything ...are you?)

2

suspended animation (you lived long ago, when things worked better, then you went to sleep or something and now it's a more backward future, fortunately you won't age to dust ala Urashima Taro)

3

reincarnation (you died of truck-kun, karoshi or a broken heart and awoke as a new person in a fantasy world)

4

prophesy (you didn't live in another world so much as see an alternate future, one you can change if you work hard)

5

regression (you lived this timeline once before, maybe more, but now you know how to do it your way)

6

summoning (you got magically kidnapped by a wizard or a god who felt bad about it and maybe gave you some benefits... there's probably a compensation law)