My apple iPhone wallet suddenly gone missing. How to get it back easily?

Hello,

It is probably still on your phone, but hiding somewhere. You should be able search for it: swipe down from the middle of any Home screen to open the search window and type Wallet:

Use Search on your iPhone, iPad, or iPod touch

If it is still not present, see this:

Redownload apps and games from Apple - Apple Support

Good luck.

Use App Library to search the Wallet app, see-> Organize the Home Screen and App Library on your iPhone

Organize the Home Screen and App Library on your iPhone - Apple Support           

If you have find the Wallet app, tap & hold on the app, then drag to the Home screen & drop it.