Had Coinbase USD WALLET EMPTIED this week while down loading coins from POLONIEX, I thought Coinbase was secure. Coinbase says they can't help. Now what.
Check your transaction history and from there do some self-investigation. There is no way someone can withdraw it easily or something as it needs authorization. Try to think about what you did along the way.
And what do you mean by
"while downloading coins from POLONIEX"?
Poloniex is moving out of the "Circle management group"
or similar, and thus everyone who is a US resident needs to withdraw all their coins, else they'll lose them. That's probably what OP was doing.
But, by using terms such as "downloading" it becomes clear that OP at the very least is not super-experienced with crypto's, or the terminology thereof.
Coinbase hasn't been hacked - your account has been hacked. Your coins are irretrievable.
Now what.
Go and change the passwords to any accounts using the same password as you use for Coinbase (there should be none since you shouldn't be reusing passwords), and go and change the password to the email account linked with your Coinbase account. I'd also check your computer for any viruses or malware such as keyloggers which may have stolen your password. Then enable 2FA on all your crypto accounts. Once you've done that, you would do well to look in to how to store your coins yourself and stop trusting web wallets or exchanges.
Do this, but if i were you, i'd also factory reset (format) your PC, or at the very least;; do some virus scans if you haven't already.
I haven't used coinbase in a long time, but is't 2FA mandatory there as well?
change all your passwords and try to be more attentive next time... that's all
That won't help if his PC is ratted.