You can track the progress of your exchange in your btc wallet (If btc to eth)/Eth wallet (If eth to btc). Can you tell us what it states? Or better yet, Send a screenshot here.

If you don't know what it looks like or where to find it. This article should help you: https://support.blockchain.com/hc/en-us/articles/115005177623-Exchanging-bitcoin-cash-BCH-for-bitcoin-BTC-or-ethereum-ETH-  (It's the 4th picture and the 5th one is where you can find it)

And don't worry you will not lose your coins. If ever the the trade failed, they will send a refund to your return address if you had entered one. If not they will ask you to contact their support and reference your TXID as well as state which address you want them to send the refund.