Ashley writes “I just started playing flute again after a 2 year break without playing at all. I played in the Symphony in college and believe that my technique is still there (for the most part, at least), but I have completely lost my tone. Any suggestions on how to get it back fast?Thanks!Ashley”
Well, the old saying about lone tones is true. Try whipping out the Marcel Moyse – De La Sonorite book and doing some of those. Also, perhaps something slow and low in an etude book would help too.
I often have to take huge breaks from the flute for surgery and find teh best cure to get your tone back is teh long tones as well. I usually just sit around with my flute and hold out different notes. Try changing the amount of air space all around your embosure to find that perfect spot again. It’s frustrating but it works in no time!
True, long tones are a great way to improve your tone no matter what.
Long tones is the best: Start with middle Bb, hold it as long as you can or at least 8 beat at 50 on the metronome; move chromatically down to low C or B, then go up chromatically to high C (C4) then back down to Bb, where you started.
This practice will take some time & be boring, but it will payoff within a few sessions. For variations, try varying the volume from pp to ff then back to pp, with each note.
Good luck.
The only way I know to get your tone back would be to just keep playing. 
Eventually your mouth will grow and shape to your flute again. I have found that playing the entire chromatic scale up and down is a big help though.
I also used to play flute in a band and on my own, and took a two year break. I have started playing again, and working on my tone. All the comments on this site are really helpful. I just wanted to say thanks to everyone who has given some feedback about this. Awesome.