First, make sure you have setup your Password Recovery questions or linked your phone number. Instructions can be found in another KB article: http://helpdesk.mhrd.org/a/solutions/articles/3000117042
If you have previously setup your recovery questions, you can navigate to https://passwordreset.microsoftonline.com/ and follow the form to have your password reset.
If you have not previously setup your recovery options, please have a teacher put in a helpdesk ticket on your behalf, or contact tech support at either building.