What can cause hand numbness, tingling for weeks?

Carpal tunnel: Statistically the most common cause by far is carpal tunnel syndrome in which the median nerve is compress as it passes with 8 tendons trough a "tunnel" bounded by a thick ligament and multiple wrist bones. Other causes include bone spurs , nerve compression in neck, elbow, root of the neck, metabolic-nutritional imbalances. If your hand is weak or clumsy see an orthopedist or neurologist.

Hard to say: There are many possible causes, but probably the most common are carpal tunnel syndrome (which is a pinching of the median nerve at the wrist), a pinched nerve in the neck, or a neuropathy. Usually a detailed exam and possibly a nerve conduction test can tell what the diagnosis is and what her options are. Thank you for the question.