R.L. Stine 
Cuckoo Clock of Doom [EPUB ebook] 

From the New York Times-bestselling Goosebumps series, a tween boy accidentally turns back time on an antique clock and now every day he is year younger. Tara the Terrible. That’s what Michael Webster calls his bratty little sister. She loves getting Michael in trouble. Making his life miserable. Things couldn’t get any worse.Then his father brings home the antique cuckoo clock. It’s old. It’s expensive. And Dad won’t let anyone touch it. Seems like the perfect opportunity to finally get his little sister in trouble for a change. But when Michael fiddles with the clock, hoping to make it look like Tara has damaged it, he unlocks a strange spell. A dangerous spell. A spell that causes Michael to get younger and younger and younger. . . .Poor Michael. He should have listened to his dad. Because if he doesn’t figure out how to stop traveling back in time, he might have bigger problems than an annoying sister. . . .