Samsung account not showing
If the app 'Samsung Account' has been disabled, re-enable it by using the following:

Settings > Application Manager > Use the right-most panel by panning right to the Heading 'All'. Scroll up all the way to the 'Disabled' part of the list, which is at the bottom, click 'Samsung Account' > Enable. 

UPDATE: expanded instructions for clarity:
The Application Manager is initially in the 'Downloaded' panel, and the column header is underlined. To the right is the 'Running' panel, and to the far right is the 'All' panel. Disbled apps are at the bottom of the 'All' panel. Select the app you want to re-enable.