hibiscus leaves turned brown

Question

Is there still hope for it?

Answer 1

Yes, there is. You need to determine if it is dead or not. This article will help with that:
https://www.gardeningknowhow.com/plant-problems/environmental/how-to-tell-if-a-plant-is-dead-and-how-to-recover-an-almost-dead-plant.htm

If it is not dead, you should be able to save it. Hibiscus a pretty resilient and will regrow leaves if they lose them as long as you continue to water it and give it proper light.