Something(e.g. work, relationship, task) had been negatively affected , but now it's normal.
Origin:
Navigation.
The planned course is called the track.
Literal use:
The pilot checked his compass, the storm had blown the small aircraft off course, but they were now back on track
Idiom:
The fog has cleared at the airport, scheduled services will soon be back on track.
After her mother died her life was a mess, now she is back on track.
Hopefully, the middle East peace process will soon be back on track.
If I don't get back on track with my studies, I will surely fail my exams.
Her mother has moved out, her relationship with her husband is back on track.
I have someone helping me at work, things will soon be back on track.
As a native English speaker I use this far more often in the "back on track" form, than the "get back on track" form.