What is the ruling on one who cut her hair from the front, less than a finger-length, after a car accident in which her sister died, with this happening repeatedly?

We do not know the reason for what you are mentioning. We advise you to observe the morning and evening adhkar (remembrances), those for entering and exiting, and for sleeping. Also, recite Ayat al-Kursi, ask Allah for well-being, and frequently recite Surat al-Baqarah and whatever else is easy from the Qur’an in the home. Listen to Qur’anic recitations often. Stay away from whisperings (waswas) and imagining what has not occurred.