Please tell me how long it takes for to recover from severe diarrhea after a colon resection?

Depends on: How much of your colon is left. If there is more than sigmoid colon left, bile binding agents can help. But if you only have only rectum left, you can still use motility-reducing agents such as lomotil (diphenoxylat and atropine). But your body will adjust over time. Make sure there is no undiagnosed c difficile infection. Consult with your surgeon or GI specialist.