I have the WiFI back, I was advised to check the device manager for anything with a yellow exclamation mark, which showed there was a problem under network, so I right clicked to update the driver and all is working now. Thanks for all the help.
Having had problems with my laptop, I have done a factory reset using a disc Dell kindly mailed to me. All seems to  be ok, but I can't access WiFi. Nothing at all shows up in Network and Sharing Center, the only options I get is to connect using an ethernet cable or via dial up. There are no WiFi options at all. I have it enabled, but that makes no difference. I have been onto the Dell Drivers & Downloads, entered my service tag and downloaded drivers, but nothing at all so far has enabled the WiFi.I have tried 'set up a new connection' but nothing shows. I think I have tried virtually everything obvious, but I just can't get access to WiFi. Any help would be greatly appreciated.
Unable to access WiFi