1. test another laptop on the connection (if the other laptop connects successfully try the other suggestion)
2. connect to the wireless network and run the windows troubleshooter
3. disable and re-enable the wireless adapter
4. manually update driver for wireless adapter(since its a dell laptop, you can go on the dell support website and download the device identifier to get drivers for your laptop) if there aren't any wifi drivers on dells' website go to device manager and grab the hardware id and do a google search to get the drivers
If you need help on getting any of these done let me know
Here are a few thing i would recommend you try:
1. test another laptop on the connection
2. connect to the wireless network and run the windows troubleshooter
3. disable and re-enable the wireless adapter
4. manually update driver for wireless adapter(since its a dell laptop, you can go on the dell support website and download the device identifier to get drivers for your laptop) if there aren't any wifi drivers on dells' website go to device manager and grab the hardware id and do a google search to get the drivers
If you need help on getting any of these done let me know