Why my front camera not working...but back camera working

@satya36543 sounds like you have a bad camera. Since iFixit does not yet have a guide for this, use something like this video to work on it. Replacement cameras are readily available at many online stores.

While you work on your phone, take lots of pictures. Once you are done with it, take those pictures and create a guide for iFixit. That will help the next person that has a device with the same issues as you do. It's easy and fun to create these guides. https://ifixit.com/Guide/new The iFixit community will appreciate this.

Repair is War on Entropy!