router

When I change the key in the Belkin N300 router with my laptop, I lose internet.
When I replace it, I regain internet on the laptop .
I usually do it from the desktop but am away. I there a place I should be entering this key in the pc, or do I need to be at the desktop to change it?
I have win 8 x 64.
Thank you

 

I just wanted you to know the issue was resolved but the cause is unknown as a few things were done. The tech replaced the Ethernet plug from the wall and commented that it was shoddy. He replaced the modem with a gateway so I have no need of my router, I guess.
My router light still acted funny so a couple of things could have been wrong. All works well.
Would you add a router to the gateway which is already a combo of modem and router(WPA2, TKIP, AES ?
Thank you for your help?