Visit the computer manufacturer's website and download the driver for your adapter and install it. If that doesn't work, then it's possible that the wireless adapter has died. Of course you also want to make sure that it is turned on. "Your notebook has an IEEE 802.11 radio for accessing the Internet through a wireless access point or communicating with other computers on a wireless Ethernet network. To turn the wireless IEEE 802.11 radio on:
1. Enable the wireless IEEE 802.11 radio by sliding the wireless network switch backward to the ON position.
If the wireless IEEE 802.11 radio does not turn on automatically, press FN+F2. The wireless status indicator turns on.
Click (Start),All Programs,Accessories,then click Windows Mobility Center. When the Windows Mobility Center window opens, click Turn wireless on." from the operators manual. Hope this helps, good luck.