Well, sometimes a hint of what the event was like is enough to bring back our memories of the event, so hopefully you can bring back that much or more. Are all the other photos as dark (underexposed) as this one?
I tried a few things, and there may be something that someone else does that can bring back more, but for this result let me tell you what I did.
I copied the original layer twice and desaturated the top layer, then inverted it and set the layer blend to Overlay - blurred that layer a bit with Gaussian blur till it brought out a bit more detail. You can reduce the opacity of the top layer a bit to see if that makes a difference to you also. Then I merged the two top layers, giving me an improved copy of the original (which is still safely sitting as the Background layer). Then I added a Levels adjustment layer to the corrected copy and brought out some more detail. I added a Color Balance adjustment layer and a Selective Color layer to work on reducing the cyan in the image. I haven't looked at your past posts to see what editing software you work with, or what experience, if any, you have at editing, so don't be put off if I'm saying things that don't make sense to you. If you know how to do them, great! If you don't know how to do them, then that's just something new to learn, and that's why we're all here!
Layers could be added above this layer - in overlay or soft light layer mode, and work could be done to lighten and/or darken specific areas - using a white (to lighten) or black (to darken) brush at low opacity. I tried Shadows/Highlights, but it didn't seem to work real well, although that might be my fault. I may try it after the saturation mask I did and see if it helps.
Oh, yes, and I used a Noise reduction program (fixing underexposure often leads to added noise in the photo) - used Noiseware by Imagenomic.