This Shabbat a chumash was on my table, I was clearing the table and unfortunately the chumash fell on the ground. Of course, I immediately picked it up. Do I need to fast as if I had dropped a Torah scroll?

Shalom, Thank you for your question. When a holy book falls to the floor one immediately picks it up (as you did). There is a widespread custom to kiss the book as a sign of respect (based on the work Sefer Chasidim 923). The custom to fast is found when a Sefer Torah scroll, or Tefillin fall on the ground (see Mishna Brurah, 40 (3)). As to fasting when printed holy books fall on the ground, this is certainly not the custom. The work Yosef Ometz by the Chidah, (page 278), he quotes a practice he saw of certain righteous people, who would fast when they saw a holy book fall on the ground. This was because they took it as a bad sign. They did this, however, only when the book fell and the open pages landed on the floor – but if it fell and the book landed on the ground closed, so only the binding was on the floor, they did not fast. However, this practice is generally not heard of today, and the custom is, as I wrote, just to kiss the book when picking it up. Blessings.