Facebook and messenger disappeared from my samsung galaxy tab 8.4
I tryed reinstalling again but it says it's already installed, I cannot find where it is,
When I hit install I only get the option to reinstall on cell that shows up all the time,
I do not get the option to reinstall on my tablet, please help.
Go into "Settings" and then "Apps". Scroll over to the "All" list and then search the list for the apps you mentioned. If they are listed there, then they are still on the device. Should that be the case, then you just need to find the icons.
They could have gotten combined with other icons, creating a folder. To see, tap any icons that look different or any folders and see if their icons are in there. If they are, then you just need to 'tap', 'hold' and 'drag' the icon back to the home screen.
Should they not be in any folder, then you just need to go to the icons list and place them back on the home screen.