Start with making sure, that your account is safe.
Take the following steps to secure your account:

1. Scan for malware. https://www.malwarebytes.com/
2. Check that the email and phone number on the Steam account are still yours.
3. Deauthorize all other devices. https://steamhost.cn/twofactor/manage
4. Change passwords from a clean computer.
5. Generate new backup codes for your Mobile App. https://steamhost.cn/twofactor/manage
6. Revoke the API key (there should be no key).

Valve is not refunding any losses from scams. You are responsible for security of your account.

해결 하셨나요? 저도 같은 거에 당했어요

你在说什么

This thread was quite old before the recent post, so we're locking it to prevent confusion.