It is possible to restore iPhone apps using either the search function or the purchase list section of the Apple App Store. Simply find the app you want to restore, and reinstall it. If the app has already been purchased, there is no charge for restoring it.
To restore an iPhone app using the search function in the Apple App Store, open the App Store application on the iPhone, and use the search box to find the name of the app that you accidentally deleted. Scan the search results for the matching app, and tap on the app that matches the description of the deleted one. Read the app information to confirm the selected app, and tap the small cloud icon to reinstall it. The app is then downloaded onto the iPhone and available for use.
To restore an iPhone app using the purchase list section in the Apple App Store, open the App Store application on the iPhone, and select Updates. Go to the Purchased section of the screen. This brings up a list of apps that you previously installed on the iPhone. To find a deleted app, tap the Not On This iPhone tab, and scroll through the list to find the app you want to restore. Tap the small cloud icon beside the app to download it, and then reinstall it onto the device.