Laptop was working on network and now will not

I have a home network with two desktops and one laptop. I am using a
Netgear WG511 router. My problem is that the laptop is not receiving
the signal. It was working fine and all of a sudden it cannot connect
to the internet. I have an excellent signal and the status box says it
is sending but not receiving. When I ping the laptop from the main
computer I get "request timed out". And the same when I ping from the
laptop to the desktop.

Thanks for your help.

Lois