If you suspect that someone has access to your login details, then you should log in and change your password immediately. Choose a unique password that you do not use for other services.
If your login details no longer work, then try the ‘Forgot password’ option on the login screen. If that also does not work, then please contact email@example.com for assistance.
Once you have successfully accessed your account, you can check the logins and activity on your account at any time by selecting Settings > Account settings.