Hello, thank you for reaching out to Microsoft Q&A.
- May I please know the exact error message your mother receives when she tries to sign in to her Microsoft Outlook account at https://outlook.live.com/mail/0/?
- Is her account locked, or is there a problem verifying her security information? When was the last time she could successfully sign in to her account?
Note- For privacy and security, we recommend providing support directly to the account owner. If her account is locked or there are persistent sign-in issues, the owner should create a new Microsoft account and then get in touch with us here. This ensures her information stays protected.