Can a bisectimy be reversed?

Vasectomy???? Do you mean vasectomy? A vasectomy is the procedure to "tie off" and occlude the vas deferens, the tubes that transport sperm to the outside world via the ejaculate. A vasectomy is reversible through microsurgery, but the success rate is not great. Several factors affect success: length of time since the vasectomy, scar tissue formation, testicular ability to produce sperm again. See your doctor.
Yes, ... Yes, vasectomy (I assumed) can be reversed under surgical microscope. But, its success heavily relies on surgeon's skill and the duration after vasectomy. For detail? Ask your intended Doc timely.