An Amount of 100 $ is debited from my credit card with unauthorised transaction.But i did't make any transaction.and this transaction shows in pending in my account.So kindly inform me that how can i get my money back from this unauthorised transaction.
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.