If your Outlook or mobile phone email asks you for your email password and it does not accept your password it could be that your password expired.
If you suspect your password may have expired try to log into the web version of your Outlook.
By the way – the Microsoft website appears to have changed. If you go to the office365.com site you should then click on the FOR BUSINESS button and then the SIGN IN link.
If the password has expired you will be prompted to create a new password. [Of course you will need to know what your old password was]
If you aren't able to access the website there may be a problem with your internet or with the Microsoft web server.
If you need to key in the server name it is outlook.office365.com