I'm going to assume you got hacked.
Before you spin your bullshit about your last logged in IP, you can make that appear as anything you want. Person hacking you could have easily logged into your account, noted down your last logged in IP, taken a hefty sum of your bank, logged out, then did a quick re-login with your IP information.
When something like this happens, regardless of what you think the cause is, you should always blame your computer first go.
Computer and network security should be your biggest concern when it is apparent you have been breached.
Wipe and reinstall (some bastards will say extreme, but it takes barely any time at all to do, especially if you way it against losing money), and start thinking about how you could have been penetrated.
Other than that, good luck rebuilding. Once you know how to make money, like you must know if you made over 300M legit, it's far easier to make it back than it was before.