I am a complete newbie. I transferred money to my coin base paper wallet before printing my private key. Now, I see my btc in wallet but could not retrieve my key by going back on my browser...Are they gone?
If you have no record of the private key stored the funds are lost forever, or more correctly you just can never spend them again. As you never had the private key stored on a hard drive, there's not anything you can do to recover it.
If you 0 currency in the CoinBase wallet you can forget that one and make a new wallet.
CoinBase is an exchange... money in cryptocurrency out. Each time You use CoinBase it automatically generates a new wallet for that Transaction.
When you login, CoinBase takes you directly to your accounts... you never really see your keys. They're automated behind the scene. So you are automatically connected to your public address (key). You can generate a new wallet somewhere else... if you have any currency in your CoinBase account you can send it to your new Wallet... the one you now have both public and private keys for.