VandhurrykannGive some more info, you can always make a support ticket and ask support for assistance.
You have to do this. I hope you already have at least started working with Steam Support, but if you haven't, go for it. Presuming someone just swiped your password and hijacked your inventory, Steam Support tends to have access to more than you can see and can probably restore your inventory.
i was about to, until i saw on the steam support page for stolen items
What is Steam's policy regarding items that were traded while an account was stolen?
Users are responsible for the security of their Steam accounts and computers, including the safekeeping of login information. It does not matter if a friend is using the account, or if the account was being borrowed by another user. It is up to the account owner to safeguard the account against such activities.