Has her ACL ruptured or is it just a partial tear?
With a partial tear, the leg is still usuable. Immediately following the tear, the dog should be placed on complete bed rest. I'm talking in the crate 90% of the day, only going outside to eliminate and doing even that onleash. No walks, no fetch, nada. Crate rest should continue for at least two weeks, if not an entire month. At that point you can start adding in very slow leash walks. Maybe walk half a block for a couple weeks, then up to a full block for a couple of weeks, then around the block. Your dog will probably never work its way up to the amount of exercise it was able to do before the tear and running/jumping activities will always be a no-no. This method is called conservative management and can be successful if really adhered to. My own 9-year-old Lab has been doing fine for the past year and a half with a partially torn ACL.
If the ACL is completely ruptured, then you should have noticed that the dog is not using the leg in question. As far as I know, there are only a few options for a total rupture...corrective surgery, amputation, or euthanasia. I could be wrong on that. Hopefully someone else will chime in with alternatives for a total rupture.