Iv forgotten my network security key for belkin g+ mimo

You may need to reset the device to factory defaults.

The manufacturers support site for the device is

http://www.belkin.com/support/product/?lid=en&pid=F5D7230-4&scid=221

The user manual is at
http://www.belkin.com/support/article/?lid=en&pid=F5D7230-4&aid=5999&scid=221

You may also be able to log into the device at
http://192.168.0.1 or http://192.168.1.1

Consult your user manual and the bottom of the product.

You can access the router's page. You just need to know the default IP address of the router. Once your able to get it, enter it into the address bar of your browser. It will ask for a router password (you need to enter the defautl password of the router or the password that you setwhen you first st it up.) Go to the wireless tab once you're able to access the router. You should be able to get the wireless network key of the router.