Your steam account has been hacked? Here below arre the procedures to retrieve it back!
What documents should I prepare? All the necessary information are on this page
If your games were purchased in a store, better include a digital photo or scan of your cd key with your steam account name written on the quick reference card or sticker on the CD key, with code in permanent ink.
If your purchase was made through Steam, provide the type of card used (Visa, Mastercard, American Express), your full name, expiry date and also the last four digits of the credit card used for your purchase.
If you bought your games on Steam via PayPal, providing the payment information of the owner's PayPal account (name and address) as well as the PayPalPayerID