Don't let your injury discourage you. My diet program (Ideal Protein) actually recommends not adding exercise until much later in program; they feel it hurts weight loss by kicking your body out of fat burning into conservation mode.
Just by focusing on diet, they prove you can still have significant weight loss.
Goal 1 - Run half marathon in early June (run not walk)
Goal 2 - Drop 100 lbs total before my birthday in late June