Hi,
First, try a Hard Reset as follows.
Shut down the notebook, unplug the AC Adapter and then remove the battery. Hold down the Power button for 30 seconds. Re-insert the battery, plug in the AC Adapter and start the notebook.
If the above doesn't correct the issue, try using Recovery Manager to reinstall your original WLAN Driver - the procedure for using recovery manager to reinstall Software and Drivers is detailed in the document on the link below.
When the reinstallation has completed, restart the notebook.
Regards,
DP-K