Step1: check your web browser and activate the “Work Offline” option. To get this option, go to the “File” tab in your web browser and click the “Work Offline” option to uncheck it.
Step2: Make sure your Ethernet cable is properly connected with your broadband modem and your wireless router. If this cable is loose at either connection point, you must tighten it before hoping to attain your Wi-Fi signal again.
Step3: Press the "Reset" button that is located on the front face, top or rear of the broadband modem. This button allows your modem to re-initialize, and this may solve your problem once it boots back up.
Step4: Enter your web address into your web browser and navigate to the page. A dialog box will appear that asks for a password, so enter the password from the manual.
Step5: Log in using default username and password. You can now change the password for security purpose(see also:How to Reset Admin Password in a Linksys Router).
Step6: Choose a security encryption and a new password to replace the old one. Make sure that you have "WPA" encryption selected. WPA is a superior encryption technique than "WEP" and should always be selected. Anytime hackers may try to access your connection and steal your bandwidth, so do not make the password too simple and easy to ascertain.
Step7: Test your Wi-Fi connection again. It should now be fixed.
See Also: Setting Up D-Link Routers
How to Lock a Linksys Wi-Fi Router