If navi that was written on a klaf falls on the ground does one have to fast?
Answer:
No, the concept of fasting for a fallen Sefer Torah applies to a Sefer Torah alone, and not to a navi.
Sources:
The idea of fasting for a Sefer Torah that falls to the ground is not found in the Gemara or the Rambam, but this is the widespread custom, and the halachah is ruled by many poskim (see Mishpetei Shmuel 12; Mahari Bruna 127; Magen Avraham 44:5; Chaim She’al 1:12).
This is extended by some poskim to tefillin that fall to the ground (Mishnah Berurah 40:3), but not to other sefarim.
Best wishes.