If your tablet won't turn on, there are a few things you can try:
Charge the device: Make sure the device is charged. If the battery is low, it may not turn on. Connect the tablet to a charger and wait for at least 30 minutes before trying to turn it on again.
Press and hold the power button: Press and hold the power button for at least 20 seconds. This can sometimes force the device to turn on.
Try a hard reset: If the above steps don't work, try a hard reset. This will vary depending on the make and model of your tablet, but often involves holding down the power button and volume button at the same time. Consult the device's user manual for specific instructions.
Check if its hardware issue: If none of the above steps work, it is possible that there is a hardware issue with the device. In this case, it may need to be taken to a professional for repair.