My email icon on phone disappeared

If the spotlight search can't find it, then its been uninstalled.

Go to the App Store, and look for "Mail". The first result should be Apple's default Mail app.

If the result has an Open button then its still on the device, if it has a cloud icon instead, then it was uninstalled. Tap on the cloud icon to install it again.

Swipe down from the middle of the home screen and type Mail into the search field to find it. If it got buried in a folder, the name of the folder will appear to the right of the app.

Swipe from screen to screen to look for it.

Reset the home screen layout. Settings>General>Reset>Reset Home Screen Layout. That will return the app to the home screen but it will also destroy your current home screen structure.

If you truly deleted it, go to the App Store and download it again.