Follow the Steam Guide here on what to do if your account was hacked.
Please click the "Submit a request" button located on this page so that we may further investigate. If possible, try to include screenshots, general dates it may have occurred, and when you first noticed the problem.
We may not be able to fully recover any items or currency that was stolen, but we will be able to provide a compensation package once we fully verify and secure the hacked account. We thank you for your understanding and patience.