How did someone successfully hack my account.
You're going to have to provide more details of how you created your wallet, how you stored it, how you lost your seed and how you found it back. Right now, your short post raises many questions that all have many possibilities depending on what you did.
From similar topics created by newbies and leaving 1-2 posts with a superficial content of their problem, a lot of questions remain, as LoyceV said, and he is definitely right. More detailed information is needed to find a solution. Beginners should take note that it would be nice to report more detailed description of the problems encountered. This will save time for everyone.
Judging by the words of retroverseworld, there is a lot of uncertainty. I even have a suspicion that ~10.78
BTC was not stolen at all, it's just that OP did something wrong and his balance is not displayed. You can easily verify this by checking bitcoin address in the explorer. Of course, if retroverseworld links the address for check where ~10.78 should be.