Ubuntu won't connect to wi-fi

Question

I've recently downloaded and installed Ubuntu on my lenovo ideapad 100, and once in a while it seems it is connected to the wi-fi, but the browser doesn't load any page; but, after turning off and on the "Enable Wi-Fi" option, it usually reconnects. Right now, it won't connect again and won't show any available wi-fi around. Any way to get the internet back without restarting the whole system?

Answer 1

Sure, are you using WPA or WEP encryption? You can use ifconfig to check if your adapter is being recognized; possibly something is causing it to be blocked or taken "down":

1. sudo ifconfig

   if you see your wireless adapter there, then move on to step 2. If not, use

   sudo lshw
   

   to see if the adapter has been rfkilled or something else.

2. 1. If you're using WEP and your wireless adapter's name is "wlan0":

      sudo ifconfig wlan0 up
      sudo iwconfig wlan0 essid network_name key network_key
      sudo dhclient wlan0
      

   2. If you're using WPA and your wireless adapter's name is wlan0:

      sudo apt-get install wpasupplicant
      cd /etc
      sudo nano wpa_supplicant.conf
      

      And add:

      network={
          ssid="ssid_name"  
          psk="password"  
      }
      

   Then press Ctrl+x to save. Controls vary using vi, vim, etc. You could use a text editor, as well.

   sudo wpa_supplicant -B -iwlan0 -c/etc/wpa_supplicant.conf -Dwext
   sudo dhclient wlan0
   

*Some information gathered from this link:
How do I connect to a WPA wifi network using the command line?

Also try this if the above does not work:

ubuntu 14.04 wireless constantly disconnects