In order to reboot the Apple Pencil you should reboot the iPad Pro by turning it on and off. If this doesnt work then you should do a hard reset of your iPad by depressing both the Sleep/Wake and Home buttons simultaneously for at least ten seconds, until the Apple logo appears.
What do I do if my Apple Pencil wont write?
For an Apple Pencil (1st generation), remove the cap and plug your Apple Pencil into the Lightning connector on your iPad. Restart your iPad, then try to pair again. 2. Go to Settings > Bluetooth and make sure that Bluetooth is turned on.
Why does my Apple Pencil connect but not write?
Make sure the tip of the Pencil is screwed on snugly ( NOT too tight, just snug ). Tip screwed properly. Tried tight/loose the tip a bit, still no response to any apps. It is so odd as this just happened after the pencil experiencing out of battery and no response after recharging.
How do I know Apple Pencil is working?
You can check if the device is connected to your iPad in Settings>Bluetooth>My Devices. If the Pencil does not appear in the DEVICES list, plug it into the Lightning port on your iPad Pro, leave it a few moments and check again.