Hi. I'm Brian and I'll try to help.
First, these forums are "staffed" by users just like you who are trying to help each other. Most of us are not Microsoft employees. No one here can call you back and you should never post your phone number or real address in public forums.
This forum is dedicated to problems or issues with classic Outlook for Windows. Is that what she was using to access her Outlook.com mailbox? If not, how was she accessing it? Has she tried accessing it by logging into https://outlook.live.com/? If not, have her try that to see if it appears there. How was her address deleted and from what application? Did you or she change something about the account and if so, where did you make the change and what was it? Please provide as many details as you can.