A tidally locked planet does not rotate in relation to its sun. One side is always day, one, always night. This is caused by tidal forces pulling all planets towards this same equilibrium, so it’s completely stable once it does occur…a tidally locked planet at an earthlike distance from the sun would be scorching heat on one side, freezing ice on the other.

What about at different distances? Is there a band of orbital distance where the night side of a tidally locked planet is warm enough for liquid water? Or one far away enough that the day side can have oceans?