Hi,
You may have to perform a hard reset to get you tablet to start again.
'''Be aware that a hard reset will erase all your downloaded apps and user data and restores your Tab to factory default'''
Here is a link that shows you how to do it. Please ensure if you can that the battery is charged or has some charge before you perform a hard reset. (see comment a bottom of page in link re charger)
[guide|24304]
Be patient, it takes a few minutes to reset.