Yesterday, I logged into my Coinbase account after a long time and ... It's empty,
I have a small amount BCH and BTC there. 2 transactions were just made and sent all my BCH and BTC to somewhere.
Before that, I did not recieve any email, or 2FA SMS.
Now I lost all and dont know why.
Have you contact the support staff of coinbase ? I think your balance can be recovered if the mistake on their site.
But if you find it the mistake because your account got hacked, then it cannot be helped anymore.
Anyway, always do not leaving your exchange account too long.