This morning, I booted up my laptop and tried to connect to the school's wireless when I noticed that the icon for Network Manager was missing from the toolbar. I checked to see that Network Manager was running and it was, the icon had just disappeared for some reason.
If you remove the notification area on the panel (right click the three vertical dots and click "Remove From Panel") and then re-add it ( right click the panel, click "Add to Panel" and search for "Notification Area", then click it) the Network Manager icon will reappear, thus allowing you to connect to wireless networks.
Note:- The above solution may not be the permenent solution
One user got this problem in a fresh install of 9.10!
So I was checking "Startup Applications" (System > Preferences) and I realized that the entry for indicator applet has the following:
sh -c "sleep 60 && python /usr/share/gnome-panel/add-indicator-applet.py"
Just after it comes the entry for Network Manager. Now I'm not sure if they're executed in the order in which they're listed and I highly doubt that also but assuming that they're executed in the same order then the Network Manager would start after the Indicator Applet and that may have something to do with the fact that it's icon is missing from the indicator applet.
So I changed the line above to the following:
sh -c "sleep 90 && python /usr/share/gnome-panel/add-indicator-applet.py"
Now the network manager's icon is there always. If the problem re-appears I'll update that fact here. But for now this change seems to have solved the issue!
I reinstall the network manager and found that nm-applet didn't show up in the notification area.
So, this is what I did and it worked for me.
1. Go to /usr/share/app-install/desktop and find Network Manager
2. Right click.. Properties.. copy the command line
3. Go to System.. Preferences.. Startup Applications and look for Network Manager
4. Click Edit and paste the command then save
5. Log out, log in
Command should be something like this
Bug Reported here
Credit Goes here