Once you reset your router back to default (factory) settings, you must re-configure all your settings (ie SSID, WEP/WPA etc) and these settings must be identical on every device that uses your network in order to establish a connection!
Once configured, reboot and see if you can ping the router using its default IP from your system. If the ping is successful, you have established a connection!
http://www.novell.com/coolsolutions/trench/9778.html
'Cant access the router using its default IP'?
Can you access the login page when you type the routers IP in your web browsers address bar and hit enter?
From there, you will need the routers default password to gain access to its configurations.
http://www.routerpasswords.com/
Also have you checked that (assuming your using XP) the windows XP driver is compatible for your network adaptor? It may pay to install the updated driver just to be sure.
http://support.microsoft.com/kb/313242
Your routers firmware is hard wired within your router and it is virtually impossible for it to disappear or be accidently deleted.
The problem lies within your routers, and/or network devices configuration setup
Good luck :cool: