What is the operating system of your Toshiba laptop? You can remove the wireless profile and reconnect to the wireless network.

My operating system is Windows 7. How to I remove the profile?

Go to “Network and Sharing center—Manage wireless network”, click on the wireless network and Click remove

I tried that. It does not work. Do you have any other suggestions? Should I change some settings on the modem router?

I think you’d better not change any settings on your router., in case other devices are disconnected.
You can manually set up an IP address, default gateway and DNS for the wireless card:
Network and sharing center—Change Adapter Settings—right click wireless network connection—properties—Internet Protocol version 4—Properties. Choose “Use the following IP address” and “Use the following DNS server address”. The IP address should be in the same subnet as your router.

Thank you for your help. I configured static IP address and DNS. See what, I am on the Internet!