I had unprotected sex on July 19th. I got my period 5 days later on July 24th and it lasted until the July 28th. I ovulated on July 30th. Is there any risk of being pregnant? I mean can sperm live that long?

Anytime you have penile insertion you risk pregnancy. The first symptom of pregnancy is a missed period. Since you got your period, there is little chance that you are pregnant. It's best, at this point, that you wait to see if your next period comes as expected.

How do you know you ovulated on July 30th?