Did you click on the - icon besides the meta general board. Clicking that would hide all the boards under 'other', such as meta, beginners and help etc.
You'll have to click on the + sign to restore it.
You could have also changed your settings to hide meta board. To change this setting, go to your profile, click on 'ignore board preference' and untick meta. Although, I believe in this case, meta would not show up in forum searches.