" FLASH IS DISABLED, THE IPHONE NEEDS TO COOL DOWN BEFORE YOU CAN USE THE FLAS ".

Hello dipankar128,

Thank you for using Apple Support Communities.

I understand that you are getting a message that the "Flash is Disabled. The phone needs to cool down before you can use the flash." This message indicates that the phone has become too hot and since the Flash generates heat, it is disabled until the iPhone cools down. So, the solution is to let the phone cool down until it is within acceptable temperatures.

Keeping iPhone, iPad, and iPod touch within acceptable operating temperatures

Best regards.

It isn't even possible, and never has been, to use Flash on an iOS device.

If you really have Flash installed in some way, then you have jailbroken your phone to do it. No one can help you. Apple will not touch your device, and any warranty is now void.