Access to clear defaults on Launcher3

[AC Question]

Hello, I'm currently running 4.4.4 on a vodafone 4G smart tablet, however launcher 3 has stopped working and will not let me access anything other than the settings menu on the dropdown box, after scrolling through the forums I have tried every fix given, I have cleared the caches and tried to change the default launcher to Google Now but I cannot access the settings to clear launcher3 as the default, the button to clear default stays dulled, all I can do is force stop, clear data or clear cache... all of which do nothing. Can anybody help at all?