ATHENS — THE sudden closure of Greece’s state television and radio network, the Hellenic Broadcasting Corporation, known as ERT, on June 11 has led to a political drama. The network’s journalists and staff have occupied ERT buildings, and large crowds have gathered to show support. With transmitters dark, broadcasting resumed over the Internet, and soon stations all over Europe picked up the feeds. Overnight, a state-run organization that had long been reviled for corruption and cronyism became the voice of a democratic resistance.