I was walking up the stairs and all of a sudden both of my legs went completely numb was hard for me to walk what can it be any ideas?

Numbness: Numbness in both legs could be related to a neck, mid back (spinal cord) or lower back (spinal nerves) or just peripheral leg nerves) problem. Possibilities are numerous. A physician may obtain adequate history and physical examination and perform adequate testing to further assist in the diagnosis. Among the possibilities to consider are: vitamin B12 deficiency, diabetes, and multiple sclerosis.