If your Office 365 password is not working, check to see if it expired. To do that go to portal.office.com and sign in. If you are prompted to select a new password, then your existing password has expired. In that case, just pick a new password and enter it twice as requested by the portal. If not, then open a support request asking us to reset your password.
If your computer password is not working, then open a support request asking us to reset your password.