Typically an Apple ID is an email address you have used.
Click on this link to read what to do "If you forgot your Apple ID" --> https://support.apple.com/HT201354
or go directly to this link --> http://iforgot.apple.com/
Also read about "What to do after [or before] you change your Apple ID email address or password" - https://support.apple.com/HT204071
If you still need help:
Contact Apple for help with Apple ID account security "This article provides country-specific Apple Support contact information for customers seeking help with their Apple ID password or other security-related issues."
https://support.apple.com/HT204169
Click on this link for general information about what to do "If your iPhone, iPad, or iPod touch is lost or stolen" --> https://support.apple.com/HT201472
- The Find My service is the only recovery feature Apple offers. It MUST be set up before the device is lost. If you did not do that it is too late to do it now and there is no other feature Apple offers that can help you find it.
Click on this link to read how to "Use the Find My app to locate a missing device or item" --> https://support.apple.com/HT210515
The chances of locating a device depend upon which features you selected in:
Set up Find My on your iPhone, Mac, and other devices - https://support.apple.com/HT210400#enablefindmy
