@Maximus I am sorry to see that this happened. I hope your platy recovers. Is the wound still fresh? If so, I would suggest using an antibacterial medication like Maracyn, or salt (if meds are not available to you). This will help prevent further tissue loss due to an infection.
As far as food, I wouldn't worry until it has been 10+ days. Your platy looks healthy and could probably go a week or two without food. Maybe try some live or frozen baby brine shrimp, as they are small and should be easy to consume. From there, maybe some frozen brine shrimp (larger ones), and then back to flake.