Turn your machine off and back on. Try to create a new block to make sure the issue is not with the last pattern that was used. Take out the battery and wait 3 minutes before putting it back in. Reboot tablet and see if anything has changed. Do this 3 times. If the touchscreen is still not responding, plug a computer mouse into the USB port in your tablet. Can you see and move the cursor? Can you click on buttons? If so, get the stylus and tap the screen directly on the pointer hand. If the pointer jumps to a different location when touched, you might need to re-calibrate your screen. Go to Main Menu>System>Interface Setup/Test>Touch calibration (For update 8.20.15 or later, go to Main Menu>Utilities>Configuration>Preferences>Touch Calibration). Follow the prompts and touch the correct areas.
If the pointer doesn't move, try dragging it around with the stylus. Moisture may have gotten into the screen and baking it should do the trick to dry it out (baking involves leaving it plugged in and on for a few hours). If you can't drag the pointer around with the stylus, or if the tablet doesn't respond to mouse clicks on buttons, call your dealer. You may need to have repairs made to the tablet at TabletKiosk.