If it isn't working, it is possible that the buttons aren't working correctly, or that there is something on the device inhibiting the reset. I would try again. Your devices buttons may be a tad touchy, which can make it harder than it should be to do this. In the end, if it doesn't work at all, you may have to take it to be repaired. Or contact the manufacturer if it is under warranty still.
NOTE: Doing this will clear 'all' the data on your tablet, so it is suggested you not choose this option unless you have to, or aren't worried about losing anything on the device.
Be sure you back up any data you want to keep, to a computer or cloud account, before doing the reset.
To "Hard Reset" the tablet...
1. Make sure that the tablet is...