You need to logon to your router -- type the gateway address in your browser (you can get the gateway from typing ipconfig /all in your command prompt window). The password will be on the wireless security configuration page.
Which password are you referring to , the one to get into the routers internal settings or the one to access the wireless home network ?
You can retrieve the wireless home network password by going to a computer that is currently connected to the network.
Open control panel and select Network and Internet and then select Homegroup , on the next page select view and print the homegroup password and the next page will have the homegroup password.