it is absolutely possible to transition to healthy hair again.
color damaged hair needs plenty of protein to replaced the layers that make the hair thin and damaged. The first thing you need to do is get a good professional trim to get rid of any danaged ends. Then you need a solid regimen that includes deep conditioning with heat weekly. Deep condition with products that contain protein like aphogee or any deep conditioner that contain high amounts of protein in it.
to get back to healthy deep conditioning is imperative along with protective styling to retain length. Stay away from heat styling as much as you can as well. Hope this helps! Good luck!