Have you searched for the app?
If you swipe to the left of the start page on your device, you’ll find a search field where you can enter the name of the app you're searching for. As you start typing, apps that match your search term will appear in a list below it.
You can also try finding your previously purchased apps and re-downloading them:
1. Open the App Store on your device.
2. Make sure you are signed in with the same account used for the original purchase.
3. Tap on Purchased from the bottom navigation bar. (On iPhone or iPod touch, tap Updates from the bottom navigation bar, then tap Purchased.)
4. Locate the app in your Purchased tab.
5. Tap the download button.