Hi Karina,
It a wiser decision NOT to do cardio in the traditional sense until your ankle heals. In the meantime you might try changing your workout in a way that not only causes fat loss, but also has longer lasting results. Increase the intensity of your workouts by getting with a professional that can map out your workout regimen with exercises that compliment each other. Then perform the routine with less of a rest period in between. Working out this way can in effect shorten your workout time, build muscle (which will increase your metabolismso you burn more calories... even when you are at rest), and burn MEGA calories while preserving your ankle. Training at a higher intensity will keep your heart rate elevated and basically kick your butt. For example doing an upper body exercise (making sure to use proper repetition and tempo to match your desired outcome) and inbetween each chest exercise filling your restperiod with stationary lunges or "air squats"... This is NOT for the feint of heart but it works. AND it is a lot easier on your body than running or high impact aerobics.

Hope this helps,

Coach Scott
Personal Trainer, Author and Motivational Speaker
http://www.phitcoach.com
Http://www.phitwerks.com

Although there are some bumps in the road, you can still move forward. Excellent cardio adjuncts include the Cycle Arm Ergometer that should be found in most gyms as well as utilizing your local pool. In the pool you can lie on a flotation board, relax your legs and paddle with your arms. You can still utilize most upper body machines and do abdominal exercises, too. To compliment your recovery & continue to maintain for the contest, reevaluate your food intake and drink plenty of water.
Always follow your doctor’s recommendations first and foremost.

Speedy reovery,

George Tabares
Fit. Spec./Asian Bodyworker/RMT

i think you should rest. you should stay off of it and recover 100% then get back into working out again. it's ok to take a few days off. i would recommend stretching : )
mo