In 1372 DR, Lolth fell silent and cut herself off from the faithful. Clerics lost their divine spells, chaos and civil war erupted, and the myriad enemies of the Drow move in to take advantage of the loss of the Dark Elves' greatest power.
This was a big thing in 3rd edition FR setting. Drow of the Underdark by WotC explained excellently of how hopelessly bound the Drow were to the Spider Queen. In short, Lolth purposefully created a society which would fall in on itself without her constant oversight. Societal revolution on a massive scale could not happen as long as Lolth kept sending her clergy to kill level 6+ Drow who didn't tow the line.
Lolth's Clerics were powerless in the chaos, and Drow faithful of other deities (Vhaeraun, Shar, Ghaunadaur, Eilestraee, etc.) became prominent. The faithful of the Spider Queen still had magic items and Contingency fail-safes, but they were at a massive loss in terms of divine power. It made perfect sense that legions of powerful Drow would abandon Lolth's worship to gain divine favors from other deities. And Vhaeraun managed to succeed where Lolth had failed, to lead many Drow to the surface world and conquer the ancient elven homes of Correllon's faithful. Vhaeraun got enough Drow to stop back-stabbing each other in order to do what Lolth had been talking about for millennia!
In 4th Edition, Lolth returned after a year-long silence and reinforced the status quo despite the large loss of dark elf faithful. She needed to move her body to a new section of the Abyss, but her cover story was that it was a "test" for the faithful. The Drow leaders welcomed her back, hook, line, and sinker; also, all the rival Drow deities eventually got killed off by her.
This is one of several things that I don't like about the 4th Edition Realms. They had changed so much about the setting, but for some reason they decided to keep this sacred cow intact. I can't see how this massive loss of power, even if Lolth left for only a year, would be able to consolidate things back. I think that it would be cooler if Lolth still had some power, but her Silence inexplicably changed Drow society, including the formation of a new nation.
My Alternate History: Lolth's Silence was one of the worst things to happen to her in terms of divine power and leadership. Her brief absence resulted in a dramatic loss of power and knocked her off the top of the Drow pantheon.
Enemies:Lolth made too many enemies for her clergy to weather out her Silence. Selvetarm, the only allied deity, is subservient to her, and his clergy are too weak and unknown (most Drow don't know that he exists) to adequately protect the Lolthites from the other big 4 in the pantheon. Ghaunadaur's got the Aboleths, the Slimes, the Oozes, and the Drow willing to work with them. Vhaeraun's got a semi-unified Drow nation on the surface world, immune to light blindness. They also have gender equality and men can be in position of leadership, and back-stabbing for its own sake is not a virtue. Kiaransalee tried to go out with a bang, and really gave the Lolthites a run for their money in the module City of the Spider Queen, but she made too many enemies and lost her faithful. And Eilestraee isn't very popular but she has a good recruitment pool among non-evil Drow. And let's not forget about the Duergar and the Illithids!
What Happened:The followers of Kiaransalee invaded the Drow cities below the Dalelands with the assistance of a monstrous army led by Karg Hellspawn. Kiaransalee's Clerics were master of undeath, and their ranks swelled with every Lolthite defeat. The Duergar invaded the metropolis of Menzoberranzan, disrupting the power structure and trade routes of the grandest Underdark city of the North.
A popular mass movement of "taking back the surface world" arose among the faithful of Vhaeraun, and the scouting parties brought riches and ancient elven secrets back to the Underdark as proof. Through persistent exposure, the Cormanthor Drow became immune to the dreaded sunlight which previously kept them confined underground. Drow refugees fled to the stability and safety of Cormanthor to escape the constant infighting. Vhaeraun attained a near-messianic status among the dark elves. The surface nations dealt with Drow raiders in the past, but not a large army, and they were downright terrified. To top it all off, the Vhaeraunites discovered the ancient secrets of the Mythal of Myth Drannor. That's right, the Drow conquered what is regarded as the greatest ancestral legacy of the Elven people. It wasn't long before Vhaeraun became the new Lolth in status and power.
Lolth returned and granted her spells back to the Drow of the Underdark. What few dark elves loyal to her were imprisoned or holding tiny bits of territory surrounded by enemies. Lolth punished them for losing their cities and dominions, for failing her. Jealous of Vhaeraun's success, she took credit for the rise of the new nation and claimed that their success was due to her. But Vhaeraun had gained too much power, too many followers, to relinquish his grasp. His Clerics reminded the citizens of how Lolth's infighting made them weak, of how her Silence nearly destroyed them. Many Drow, especially former Clerics who yearned for the old days of matriarchal supremacy, believed Lolth's lies and tried to seize Cormanthor in the name of the Spider Queen. The surface elves, fresh from their Retreat to Evermeet, returned to their homeland to take it back. And thus the War of Cormanthor began. This is the ideal point for a new campaign to start.
TL;DR: So we don't go back to status quo, leave if off at 3rd edition, and still have Lolth as a force to be reckoned with yet suffered consequences for her silence. We've also got a big war and a new powerful Drow nation on the surface.
