How do I restore my AOL EMAIL ACCOUNT to my iPhone

The typical method to restore an email account would be from a backup of the iPhone that was being made either to iCloud or to a computer.

• Restore your iPhone, iPad, or iPod touch from a backup - Apple Support

If your goal is to just re-add the email account, then you should be able to do so following this support article:

• Add an email account to your iPhone, iPad, or or iPod touch - Apple Support