Check if you had a subscription set up... Click on the profile tab (icon next to log out) > Click on payments third option along on the thick blue band top of page > "manage pre-approved payments''.
If not then if you were hacked...
Click on the transaction in your paypal account and use the 'report a problem' link at the bottom to report it as unauthorised if that is what it was.
An unauthorised transaction means that your Paypal account was hacked and used without your consent. If Paypal check IP addresses / devices etc and find that it was hacked then yes you should receive your refund.
I hope you changed your password and security questions? I hope you ran a virus scan on your computer? I would also be telling my card issuers and bank accounts company that the account was hacked so that they can keep an eye on your account OR remove the financial info involved until things are sorted.
Advice is voluntary. Kudos / Solution appreciated.