If you have direct access to your router you can reset its configuration and then your default password should be reseted as well it usually will be written on the back or under your box.
Some routers also have a way to login by pushing a button on the box physically but newer models where I live do not have that so it depends.
Most common default passwords are:
admin
password
the wifi default key
In the case of your model there should be a sticker like this on its back where you have all the default values written:
Hopefully that helps!
