The SSID is the name of your network. It should be broadcast by your router, and show up in the available networks list. It should not be hidden.
Are you talking about your WPS or WPA key instead?
Why can't you just change the key?
Some routers make the WPA key essentially write-only. You can set it, but you can't read it back out. So if you forget it, you have to just change it, along with changing every other device that accesses that AP.
yup so you blow it to factory config. and reset the router and every device back up then write the darn key and ssid on the bottom of the router - the safest place for you.