Hi, welcome ot Android Forums, I'm sorry it's taken so long to get to your question.
I'm not sure of your specific model of tablet, but try shutting the power down on your device. When you power on the device, continue to hold the power button down along with the volume up button. This should get you into the recovery menu. Try doing a factory reset on your device.
Again, without knowing the specific make and model of your device I cannot walk you through the process.
Sorry I cannot help you further.