Do cows die if tipped over?

The possibility certainly isn't a remote one. Cows that lay down for days at a time due to injury or illness will first suffer from dehyrdation and starvation, second only via muscle deteroriation and consequential weakness in musculature and ligaments. Blood cannot flow to a cow's legs when they are bent up for too long, which may eventually cause the first stage of necrosis, or just a tingling/numbing sensation in the legs due to circulation being cut off and being unable to reach these extremities. But basically once a cow is down and can't get up, and even after attempts to try to get them back on their feet again that have failed, it is in the best interests of the cow to euthanize her rather than leave her die a slow, painful death.