How to change change field value?

How to change change field value?

I have a requirement to handle emails of no response 
Case1: when the notification was sent, and there's no reply within 3 days then close the ticket 
Case2: when the notification was sent, and the customer responded then abort time counting and back to the normal flow

I've tried to use the Business rule and Trigger but still not successful. Could you please help suggest? 
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