Replacing just the Interior Door, if the frame is in good shape.
Interior doors can take a beating in there life time. Especially with kids and pets around.
Many of todays interior doors are what they call a hollow core door, meaning they have 2 outer skins on a frame and hollow in between.
When one gets a hole or crack in it they are hare to repair and still look good.
If you have an interior door that needs replacing, They aren’t that hard to do if you are handy.
You are going to need a few tools and a little bit of knowledge. You can do it with basically a screw driver or screw gun preferred. Hammer and wood chisel. ( a rotor is helpful), tape measure, pencil and square and a couple of hole saws.
Here is a great video on the basic way to do it.