If you get an email about unusual activity on your Microsoft account, or if you’re worried that someone else might have used your account, go to the Recent activity page. You’ll see when your Microsoft account was signed in during the last 30 days, along with any device or app-specific info. For answers to common questions, including how to get back into a compromised account and secure or close it, see What is the Recent activity page?
If you're concerned that someone might have access to your account, we strongly recommend that you change your password and update security settings. You can do that on the Security settings page, where you can also remove all trusted devices. To learn more about account management and security, see Security basics.