My Steam Account Compromised. Items Sold Without Consent Despite Two-Factor Authentication

Somehow, someone managed to access my Steam account and sell the cards I had earned from games on the Community Market. They then used the proceeds to purchase other items.
I have Steam Guard enabled, which sends a code to my phone that I need to enter to log in. I've never shared my account with anyone. I only buy and play games within my budget. I've reset both my email and Steam passwords. I want the sold items to be returned and the individuals who profited from these unauthorized trades to be banned.






