BWOOM! You fly away from the earth in the speed of light, and you're no longer an event in the dimension of spacetime.
But the time on earth goes on..
When you then turn back, still travelling in the speed of light, and you eventually reach the earth, you're back in the exact same second as you left.
Wich, kinda makes you travel back, but, infact doesn't make you travell anyway at all.
TWhen you travel very fast the time goes slower for you, that means if you travel very fast for a year, you will be 1 year older, but in the place where you left everyone will be >1yr older. That means they will get older than you and which also means that you traveled into the future.
uh.. right..