There are a lot of questions about the time turners in Harry Potter. There's a fan theory that Ron could have used one and become Dumbledore at some point in the past (but that's been debunked). I also asked Why Couldn't a Time Turner Have Been Used to Stop Voldemort?. It seems that Rowling had them all destroyed to stop time travel issues (such as paradoxes or the idea that one could be used to just undo all the bad with Voldemort before it started).
The time turners are magic machines, so they had to be created at some point. But are they the only way to time travel and why couldn't one use the same type of magic a time turner uses to move back in time more than just an hour?