try resetting your router, then going to your router page (it will be a number like 192.xxx.xx.x or something) and going into the router settings:
if you're using a wireless connection you'll need to set your router to the WPA-Key option and then click on the button that lets you generate the codes. (it's usually a ten digit code made of letters and numbers and it's called a hex key i think) use this code when setting up your ps3 for wireless. it might not work, but it's worth giving it a go if you haven't already done it
BUT, you'll need to know your router username and password to access the settings (the username is usually the name of your provider e.g. 'virgin' and the password is usually 'admin' or 'password' or something)