I know Stargrass will react to insufficient nitrate by becoming transparent and melting suddenly. It does well in a tank that is well-lit, well-fertilized and with CO2 supplementation. If you have those conditions, I would expect it will turn around. Just trim off the worst parts.
"We are living on this planet as if we have another one to go to". T. Swearingen
I have had better luck floating the plant for a couple of weeks. You will get a lot more new growth that way. In a related note, in my experience stargrass simply does not ship well. Especially when it is hot.