any idea about how to solve iphone ios7 no sound from external speaker issue ?

Hello Hhamaky,

It sounds like your speaker on the phone is not outputting any sound. I recommend the troubleshooting from the following article named:

iPhone: No sound or distorted sound from speaker

http://support.apple.com/kb/ts5180

1. Verify that the volume is set to a level you would normally be able to hear.
2. If the iPhone is in a protective case, make sure that the speaker port isn't blocked by the case.
3. Make sure that the speaker and dock port aren't clogged with debris. If necessary, clean it with a clean, small, dry, soft-bristled brush. Carefully and gently brush away any debris.
4. If the iPhone is paired with a Bluetooth headset or car kit:
   • Try turning off Bluetooth.
   • If you experience difficulties with the Bluetooth feature, follow these troubleshooting steps.
5. Restart the iPhone.
6. If restarting doesn't fix the issue, ensure that your iPhone is updated to the latest version of iOS.
7. If the issue is not resolved after restoring the iPhone software, pleasecontact Apple Support.

Another thing you can try is backing up the device to your iTunes library with this article:

iOS: Back up and restore your iOS device with iCloud or iTunes

http://support.apple.com/kb/ht1766

Then restore your phone with this article:

Use iTunes to restore your iOS device to factory settings

http://support.apple.com/kb/ht1414

Thank you for using Apple Support Communities.

All the best,

Sterling