Is selling musical tapes forbidden (haram)? Is the money earned from it forbidden (haram)? Does the principle that a supplication is not answered for one whose body has been nourished by forbidden (haram) things apply [in this case]? And what should be done in this situation?

Selling tapes of forbidden songs is prohibited, and their price is ill-gotten. The Prophet, peace and blessings be upon him, said: "No flesh that has grown from ill-gotten wealth will enter Paradise; the Fire is more befitting for it." Consuming unlawful earnings is one of the impediments to the acceptance of supplications. It is obligatory for anyone who trades in prohibited items to repent immediately, cease the unlawful work, and dispose of the price of the unlawful items, except in cases of necessity. And whoever repents, Allah will accept his repentance.