Microphone is not working in iPhone 4s I know this question is a poor one but I don't know what happened to my iphone i am using it from past 2 years but its microphone suddenly stopped working and i am having problem in recording voice notes and calling. But mic is working in Videos. I am not understanding the problem. It is my one of the favorite phone that's why i don't want to get rid of it.

Here is list of problems i am facing in my phone.
 1. Having problem while calling
 2. Not having problem while recording video
 3. Having problem while recording a voice note
 4. Microphone starts working when i switch my call to SPEAKERS.

I hope everyone understood my problem. Waiting for the possible easy solution.
It sounds like one of the two mics on your iPhone 4 has failed.  One is used for phone calls and the other is used to pick up ambient noise for noise cancellation and is also used during speakerphone calls and video recording.

If you replace the Dock Connector, that'll get you a new ambient mic.