Can't connect to the internet

I'm using windows XP and having trouble connecting to the internet.  I had a connection through a router, but after a shutdown it suddenly no longer had a connection.  The icon in the network connections that says internet has disappeared and I can't get it back.  I've tried the connection wizard, the router setup disk, and reloading windows.  I've tried even system restore, but it said that no system changes had occured.  Any assistance is greatfully appreciated.  Please email me.  I'm using an alternate computer for now.