Hello Lugesh,
Thanks for asking the Apple Support Communities for help with your iPhone speaker.
I recommend going through the troubleshooting in this help article: If you hear no sound or distorted sound from your iPhone, iPad, or iPod touch speaker - Apple Support
If you still have issues, please have the device checked at an Apple Authorized Service Provider or Apple Store. Please review this help article prior to bringing your device in to be checked: Get your iPhone, iPad, or iPod touch ready for service - Apple Support
You can find a service provider using this link: Apple Find Locations
Thanks and have a wonderful day.