no phone sound

Solution
Do other sounds work? If no, then it could be the speaker. If they do work, then it is more likely either the sounds are turned off, the volume for the ringtone is turned down (they are separate from other sounds) or even the ringtone you were using was moved or deleted, which could make you have no sounds when a call comes in. Another possibility is if you have any apps that were recently installed. They could be messing with your sounds.
Do other sounds work? If no, then it could be the speaker. If they do work, then it is more likely either the sounds are turned off, the volume for the ringtone is turned down (they are separate from other sounds) or even the ringtone you were using was moved or deleted, which could make you have no sounds when a call comes in. Another possibility is if you have any apps that were recently installed. They could be messing with your sounds.
 
Solution