If you want to log in / sign in to your office applications like : Outlook.com, Skype, OneDrive, and Xbox Live you need your username & password for it.
If you you forgot the password you use to sign in, then you need to reset your Microsoft Account password.
For complete application visit office.com/setup website.
How to Reset your Microsoft Account Password?
Go to the Reset your password page.
Choose the reason you need your password reset, then click Next.
Enter the Microsoft account email address you’re trying to recover.
Enter the characters you see on the screen, then click Next.
If you have security info on your account, we’ll send a one-time code to the alternate phone number or email address you gave us.
After you enter the code on the next screen, you’ll be able to make a new password.
for more details, visit: www.office.com/setup.