Hi Deborah and wlecome to Vista Forums
Do you have your router permanently powered up? It is possible that loss of power has caused your router to revert back to its default settings (the same as you would get if you manually reset it). Check its configuration settings by entering
http://192.168.0.1 (or the address given in your router's documentation) in the address bar of IE7 and make sure that everything is set correctly, especially the WEP/WPA/WPA2 password (this needs to be identical to that on your laptops in order for them to connect wirelessly - this would explain why they cannot connect via the other router). Refer to the router's documentation and make careful notes as you go on so that you can refer to them again if the need arises. Once you have got your laptops connecting, go back into the router configuration and choose the option to backup your settings. If the same thing happens again, you should be able to use this file to restore your router. Note that setting up a router needs to be done via a direct wired Ethernet connection.
To check all this, power down your router and wait 5 minutes. Power it back up. Are you still able to connect? If not, connect via Ethernet and restore your settings using the backup file you created earlier.
Another possibility is that your router automatically turns off the wireless output on power failure and that this needs to be manually re-enabled.