Car wouldn't start, was told I needed a starter. After replacing the starter, the car still wouldn't start. I remove the new starter to inspect the fly wheel, but it won't move.

Depending on the vehicle, the water pump, for instance, may have seized.

https://www.askmehelpdesk.com/cars-trucks/when-asking-about-your-vehicle-303903.html

Tell us more about what you drive and we can give more specific answers.
Thanks!