Follow this sequence to reach Device Manager.
1. Click on Start Menu / Right-click on Computer / Click on Manage.
2. Click on Device Manager on the left column, and then double click on Network adapters.
3. You should see 2 adapters, double-click on your wireless adapter to enter property.
4. Go to Advanced tab, select Radio Power and make sure it's set to Enabled.
5. Try your wireless connectivity again.
If it's already enabled, just disble and enable ..
It works! .. Rakesh John