There were two revolutions in Russia in 1917: The February Revolution, which supplanted the tsar and established the Provisional Government led by Dr. Alexander Kerensky; and the October Revolution, which brought to power the Bolshevik wing of the Social Democratic Party and paved the way for Communism and the Soviet Union. http://en.wikipedia.org/wiki/Russian_Revolution_of_1917
What if the second revolution had never happened?
Putting this in perspective – except for the Cadets (Constitutional Democrats) and Oktobrists (constitutional monarchists), all the major political parties and factions on the scene were socialists – although they had very different ideas about what “socialism” meant. Kerensky’s Social Revolutionaries (http://en.wikipedia.org/wiki/Socialist-Revolutionary_Party), for instance, were mainly based in the peasantry and their main issue was land reform – meaning, they wanted to take land from the landlords and distribute it to the peasants in family smallholdings*; whereas the Bolsheviks wanted the land nationalize or collectivized. So, even without a Bolshevik revolution, what emerged might have been, or called itself, a “socalist republic” of some kind or other.
Even after the Bolshevik Revolution, there were free elections (they had been scheduled before the Revolution) to a Constituent Assembly, charged with drafting a new constitution. The Bolsheviks received only between 22% and 25% of the vote, while the SR’s got a majority – http://en.wikipedia.org/wiki/Russian_Constituent_Assembly:
Lenin allowed the Constituent Assembly to meet for one day and then had it dissolved at gunpoint. But if Lenin had not been in power at that moment, what kind of republic might the Assembly have produced for Russia?
There were also the “soviets” – http://en.wikipedia.org/wiki/Soviet_(council) – mostly impromptu, self-organized committees of workers, soldiers, etc., which, at this point, were independent of any political party. A lot of people believed the soviets should be given real political authority, or argued that they already had it, and legitimately (the situation was confused and chaotic, of course). In practice the Bolshevik slogan “All power to the soviets!” turned out to be a euphemism for “All power to the Bolsheviks!” But suppose it had not turned out that way? Could the soviets have survived, as a bottom-up locus of authority independent of the state’s institutions? What would they have done with that power?
*On that note, see this recent thread on “distributism”: http://boards.straightdope.com/sdmb/showthread.php?t=344179