What a fine question.
Well, as I am mainly an egocentric person, I'd travel to my early years, learn how to play guitar and then I'd create a band named, lemme see... er... Beatles yeah !
I'd make a fortune and by now, I'd have all the time in the world to scrub rabbish on HP without having to go to work every morning.
No, no, I'd not like to change the course of events. Just me.
And I'd add here and now boys ! Karoonah !