If you've never registered your account, you will need to do this step before you can reset your password.
1. Go to https://passwordreset.microsoftonline.com
2. Enter your email address and the captcha code. Click "next"
3. Enter phone number or alternate email address to authenticate your identity. Select your preference for receiving a new authorization code, and click "Call", "Text", or "Email."
4. Once you receive your code input it into the site. Click "Next"
5. Enter your new password and confirm it. Click "Finish"
Your account password should be reset and ready for you to use.