Instructions
Log into your router settings page via your Web browser and manually check the security password. Open your Web browser and type your router's IP address into the address bar. This IP address will be listed in the manual that came with your router. Use the user name and password for your router (which will also be listed in the manual unless you have changed it) to access the setup page. Click "Security" to view the current password.
Speak to the person who set up the wireless network you want to access. If you had a friend or family member set up the wireless connection, this person specified your wireless network security key. Write it down so you will have access to it for not just your PlayStation 3 but for other wireless devices, as well.
Call the company who you have Internet service with. If you are a Verizon FiOS customer, for example, you would call customer support for Verizon FiOS. If you are an AT&T customer, call AT&T. Contact information is listed on your bill as well as on the website. If a representative from the Internet service provider set up your home wireless network, the password used when creating the network will be noted on your account.