If you miss your flight [where you have not changed or canceled your existing booking] then you have no idea.
You must specify the fare rules related to your ticket. In most cases, the fare rule states that NOHOW tickets are no refundable. In some cases, even if you do not charge some amount as a show airline penalty, moreover, to change the penalty or cancellation penalty and airlines refunds the amount applicable to you or you receive your option at an alternate future date. Give tickets Allow to change.