After witnessing the man in the yellow suit a.k.a the Reverse Flash attack the Flash, many things have come to light.
1. The Reverse Flash is Harrison Wells
2. Harrison Wells uses a ring to control the Reverse Flash.
3. When the Reverse Flash and the Flash come together they conduct electricity
4. Barry saw this electricity when his mother was murdered.
After reading comics and researching. I have finally come to one conclusion and theory. This spoiler is from the comics.
Barry Allen is the fastest man alive with incredible speed. Since he has incredible speed he will be able to run so fast, so he can go back in time. That's one.
Two. The Reverse Flash also known as Eddie Thawne has been a big fan of Flash. In the series, Eddie can't stop thinking about Flash when Flash attacked Eddie in the Arrow Crossover.
Three. In the comics, Eddie get so angry about the Flash that he goes to Harrison Wells and asked for Super Speed but only in the reverse way.
Four. Since Eddie has the power, he wants to terminate the Flash. So he goes back in time to kill Barry as a little kid. But Eddie wants to kill the mother before Barry is even bore.
Five. So The Flash finds out about this and goes back in time to stop the Reverse Flash from killing his Mother. Thus starts the electricity that Barry saw when he was kid.
Six. In order for the Barry in the past not to die, the Barry in the Future takes him out of the house. So he can kill the Reverse Flash.
Seven. But Barry is too late and Nora Allen is dead. This means Future Barry has to go back to the future leaving Present Barry to become the Flash.
So there you have it, the truth behind all of it.
If you watch the mid-season finale, The Reverse Flash doesn't kill Eddie Thawne for a good reason. There is no need for me to tell you why he didn't kill Eddie.