If you want to portforward or something, you usually have to have the user and password. I know my Username is Admin and the Beginning password was Password1 or what ever. But, I forgot the pass I made?
If it was set to admin, admin1, password, or password1 Verizon probably changed it a few months ago to be the serial number of your router. Give that a shot (it is case sensitive!). If it doesn't work you'll have to reset the router to factory settings which will reset the password if anything to admin/password or admin/Router's Serial Number. The least it will do is ask you to set a password when you visit the router's web interface.