Harry Potter theory - couldn't he just use a time-turner to go back and save Sirius, Lupin, Fred, etc?

A few years after Voldemort was defeated forever (to give him time to recuperate), when the time-turners are restored to the Ministry, couldn't he just go back to, say, when he was in 3rd year (as the location of the diary was unknown beforehand) and destroy all the Horcruxes as he knows where they all are? If all else fails, he could just go back and capture Wormtail to prevent Voldemort from rising again anyway - aided by the invisibility cloak of course.