Assume that the future can change based on your actions, so any historical information that you bring along with you from the intervening 25 years may quickly drift out of the new realities history.
Edit: also assume that you can be given a healthy 21-year-old body if you want or take your previous self’s place.
Further, identification will be provided for you if you were not born at that time.
Have you ever seen the TV show quantum leap?
That’s what I’m talking about. Your personality, the wave state of your brain that makes you “you” would take over your former selfs body.
Once again though, if that doesn’t work for you, you could just have a new body.
If going back to 1999 would put you into you infant or toddler’s self, then the appropriate choice would be to get a new body.
Ah so you basically reset your life. No thanks