Which wireless network adapter do you have?  Is Windows managing your wireless network or is the utility that comes with the wireless adapter managing your wireless networks?  The wireless connection tab does not appear if the adapter's utility is managing your wireless network.

 

If this doesn't help, you need to tell us more about your wireless network?  Is it's SSID hidden?  Are your using encryption on the router?  Is MAC address filtering enabled on the router?  Have you ever been able to connect to this wireless network before?

 

Steve

the network  adaptaer is Intel PRO/wireless 2200BG network connection

I don't know if it is windows how is managing the wireless netwwork  and the SSID is no hidden Iam  using wpa pre share-key  but when right click on the wireless icon  and I click on View Available  Wireless  Network, it does not show  any network. I could see it before  but no now

 

Make sure the wireless radio is turned on (the Fn F2 key combination toggles the radio on and off).

 

Open the Dell Proset Utility and uncheck the box so that the utility is not managing your wireless network.    Now go to Network Connections, right click your wireless connection, select Properties.  Now do you have a wireless networks tab.  If so, click on that tab and make sure the box is checked to Let Windows manage your wireless networks.

 

Steve