You really need to post a bit more info that that if you want help!
Have you just joined 48 and are having trouble?
Or have you been here a while and it was working before?
If so when did it stop working and did anything change on your phone - e.g. you were abroad and came back, software update, settings update?
If you do a manual scan for networks can you see and connect to 48?
What make and model of phone do you have?
Hope this helps.