after installing ios7, my apps disappeared. how do i get them back?

They are most likely on a differnt page. Swipe all the way from right to left.

Those that are still in the store will show in the Purchased tab in the App Store app for re-downloading, or (if they are on it) you can sync them back from your computer's iTunes.

Yeah me too having this issue with iOS 7.0.2, apps are just disappearing randomly, not all of them, I had to re download them from App Store. And it happened few times. I believe it's a bug in iOS 7