Re: IF you had a time machine…
Ok, I would so wish to go back in times when Prophet (S.A.W) was alive so I can be with Him, learn from Him, serve Him but then considering that we don’t do our job today (even though it’s easier now with all this technology etc), I’d be a hypocrite with what I said above 
I would also like to go back when Zul-Qarnain was there and also time of Sahaba and Tabioon.
There are few more.