How can I unlock iPhone7 by its serial number
Apple Watch
If she forgot the Apple ID (iCloud) password, enter the Apple (iCloud) ID, and click Forgot Password. See if she can get a Rescue or Notification email option if necessary. Link to contact Apple Support at the end of the 2nd article.
Assuming that you mean passcode: If you forgot your iPhone passcode - Apple Support
You cannot. You need your Apple ID and password (account), passcode (to unlock device), or carrier (for service), to unlock it.
The iPhone7 waa a gift from Mom and also she has forgotten the password to the account
Yes it's about forgotten password how fast can I get it back from support community
Can I use the serial number to Unlock my iPhone
