Play Store disappeared from Samsung Galaxy-GT I8730- Android version 4.1.2.

[AC Question]

I followed advice about going to Application Manager-downloaded-running-all- with no turned off option, and went to end of "all" and there is no there was turned off button there either, and the play store icon is there but holding down the button does nothing. The icon also appears in the downloaded section but there is no way that I can see for activating it.