Could Barry save Laurel?

I'm curious as to why Oliver didn't ask Barry to go back in time, he's aware of this ability, and he told Lance he would do anything.

Well he lied and besides Barry told him that things always go to the worst with Time travel (eventhrough that is never true)

that is always true, barry stupidl(suprose suprise) uses time travel to talk with prof and he almost gets everyone killed(again)

I hope not.