Starter issue, battery is good?

I do not know if it is related but the last two times that I went to get gas my car did not start right away. After getting gas and driving home the last time, with no issues on the way. The next morning it did not start. I checked my battery and had proper voltage, as well as the 12 volt constant and the trigger wire. The flywheel was not seized. Or however you say that forgive me I am not familiar with the term. And I don't know what to do to troubleshoot from here please help me