Start by figuring out why those spots are there. What caused them? Did you water deeply and infrequently last season? Are the spots in deep shade? Did you have pets or kids tearing up the grass? Did you mow at the mower's highest/lowest setting? Did someone poison the soil with motor oil or whatever?

As for recovery, are you willing to water as needed? Mow weekly? Fertilize in late spring, late summer, and late fall? If not then you could let some lesser grasses and plants (what we usually call weeds) recover the area for you and just mow as needed.

Some of the pictures look like the soil was or is quite wet. Do these areas have a drainage problem? Of so before you, worry about grass you should develop a plan to drain these areas.

If there is a drainage problem it may not have shown up in previous years as it has been colder and much wetter than normal years.

Thanks 😊