Is the damage in the brickmold or in the actual door frame?

Brick mold is easily replaced. It is simply trim.

The frame itself is repairable to some degree, depending on how much actual damage it present.

The damage will have to be examined in person to determine the extent.

If it's just the brick mold or other wood trim on the outside face, you could cut out the bottom few inches and replace it, on both sides of the doorway, with plinth blocks. This can serve to dress up the door a bit and be easier to periodically replace than the entire brick mold as moisture absorbtion from snow and rain causes wet rot. If the trim is painted, you can make the plinth from PVC, it won't rot and you won't be able to tell that it's plastic.

Menard's, Home Depot, Lowe's, any good lumber yard.