Help! with Very old unused sourdough in my fridge

Three years is a very long time so you might have lost it, but you can try. I've revived cultures that have been neglected in the fridge for the best part of a year.
The separation is no problem, nor is the alcohol smell. That's 'hooch', a product of the yeast in the culture.  You can discard it. What's important is the white, probably quite solid, stuff underneath the hooch. If it smells horrible (like something died) then throw it away. But if it smells ok, you can try 'washing' the culture to revive it. Here's how...
Transfer the culture to a clean jar (e.g. a 1 litre jar) as best you can. Fill the jar half way with with cold or tepid water (not hot !) and stir vigorously for a while trying to mix as much of the solid stuff into solution. This might take a while. You will end up with something that looks like weak milk. Save one cup of this (no solid bits) and discard the rest. You might need to clean the jar if there is goop in the bottom or swap to another jar. Put the cup of saved liquid in the jar and begin stirring in plain flour. Add enough so that you get very thick batter consistency.
The above is a washing cycle :)  Leave the jar in a sheltered place (not too cold). The next day, repeat the whole process. What you're doing is trying to create conditions that benefit the sourdough organisms and retard any contaminating organisms.  
Keep doing this until you start seeing activity (bubbles, froth, mixture rising in the jar, nice smell). I've had to do it for four or five days sometimes.
If your culture had died nothing much will happen.
Good luck !Michael