How to lighten a dark picture?

Please help! I took a picture last night outside with my friends but it was very dark outside and I forgot to turn the flash on (I did this with my iPhone).It would be a perfect picture if I could see our faces, but I can't because it's so dark. Is there anything I can do to lighten it so that I can see our faces? Any ideas will help.

We have no idea just HOW dark it is?: We have no idea of what, if any, photo software you have? We have no idea of your skill level with software?

So how is anyone supposed to be able to give you any suggestions on how to brighten the photo, if it can even be done.

The best thing for you to do is put the photo on a site such as Flickr or to Post My Image and submit the link to it with your question.

Once we can SEE the photo, I'm sure there will be people here who will try to lighten it for you. Be aware though, that will typically generate lots of ugly digital noise in a photo. It is in no way a "perfect picture" except for being too dark, as you will see if people try to force more light into it.

There's pretty much nothing you can do in that case… Besides maybe going back in time…

Try putting the picture into an editing app and adjust the brightness.

Load it on to your computer and open it in your Pictures programme.
There should be a basic screen for enhancing photos. Just slide the Brightness slider to the right to lighten the picture.

However, this will only work if there was enough light in the first place. Having realised on the screen that the picture was too dark, why didn't you immediately take another with the flash turned on!

Try this http://pixlr.com/editor/