Hi my name is ***** ***** i will be assisting you today.
I am sorry to hear that you are facing problem with your Samsung galaxy tab, i will try my best to resolve the problem at the earliest.
What is the model number of the galaxy tab?
push and hold down the power button on the tab for 45 seconds
keep it pressed and hold it down
release the button.
look for a tiny pinhole reset button at the back
use a paper clip and then push and hold down for 10 seconds
reply back after you try these steps.