The technology has come a certain way, there is now an app approved by apple on the App Store that restores deleted data back to your iPhone
When you delete data from an iPhone, the deleted data still remains on the iPhone's database and can be recovered by various types of smartphone recovery software.
It is recommended that when you delete items from an iPhone by mistake, or if an iOS update deletes your data, that you stop using your iPhone until you recover the deleted data. This way you will lessen the chances of you overwriting the deleted data by creating new content on your phone.
Smartphone data recovery software is out there, you just need to do a quick search, read reviews, check prices and make a choice.
Good Luck :-)