Three Years ago, At&T Inc. executives were in a federal courthouse battling the Justice Department to defend their takeover of Time Warner Inc., a more than $80 billion raid into the entertainment industry.AT&T won the court battle, but lost in the marketplace. Now, with the instruction of Chief Executive John Stankey, the telecom behemoth is giving up its dreams of marrying distribution and media content-one of the largest turnarounds in corporate history.AT&T stated on Monday that it will spin off its rambling media empire, including HBO, CNN, TNT, TBS and the Warner Bros. studio, into a new venture with Discovery Inc. That follows a February agreement to hive off a 30% stake in satellite broadcaster DirecTV and give in operational control of its pay-TV unit, which was hollowed out by clients trading pricey channel packages for cheaper alternatives. All told, the two reversals got rid of tens of billions of dollars of equity value, as AT&T cut deals to exit its investments and shed debt. AT&T stated that the full value of the media transaction includes not only equity value but also the cash AT&T will receive for the divesting itself of the business.