Apple Pencil charging

Yes, leaving the pencil uncharged for that many months killed the teeny tiny battery in the pencil. The batteries in them require being charged all the time. Once they die, they are dead and cannot be brought back to life. The only option at that point is to buy a new pencil and remember to keep it charged.

There are two ways to charge an Apple Pencil 1st generation

1 - As Quickpost said - plug the pencil into the lightning port on your iPad, when you check battery widget it should show the pencil as charging

2 - Within the box of your Apple Pencil you got a lightning adaptor which you can plug one end onto the end of your pencil and the other end onto a lightning charger. I prefer this way as it means I don't have a pencil sticking out my iPad Air where it could get damaged.

If you have left your pencil for a while without using it could mean the battery is damaged and can't be charged

Apple Support information about charing pencils - Charge your Apple Pencil and check the battery - Apple Support

Do you have your battery widget on?

If not have a look at this - Use widgets on your iPhone, iPad and iPod touch – Apple Support

Its a really good widget to have for the pencil so you can check the charge

Hello,

Remove the cap from the top of Apple Pencil and plug its lightning connector into iPad’s charging port.

The battery is dead, thats the issue

You're welcome and I surely hope your health issues are far behind you and the loss of the Apple Pencil is the worst of your worries.

Stay safe and healthy!