screen is cracked but touch and display is working good can i change the above galss in my iPhone 6s

Apple and any repair that an authorized agent would do would be a complete replacement of the entire screen assembly - glass/digitizer, LCD, and I believe the home button.

The glass/digitizer is actually glued to the LCD. It is possible to separate it and reinstall just a glass fix. However, I've seen such repairs and often they look pretty bad since the gluing process is done by hand (compared to the OEM process which is automated). There can be cosmetic (or even functional) damage to the LCD when it's separated from the broken glass. Usually this means the home button is reused and there can be problems with Touch ID if it doesn't go through Apple's repair equipment.

Overall I wouldn't recommend it. The cost from Apple is only a little bit more than third party replacement with an aftermarket part. And I don't really recommend glass only because of the reasons I mentioned.

MANOJmathan wrote:

Does apple service centre can change the upper glass gently?

It really depends. When Apple or an AASP does a replacement, it's done as a complete replacement of the screen assembly. For an iPhone 6s, that would be $149 plus tax in the United States. It may be a different price if done by an AASP and/or in other countries. Apple will not replace just the glass. Also - I don't believe that Apple will repair them and put them back in service for the same customer. All replacement screen assemblies should be new.

Also - in some areas or for many AASPs Apple doesn't make the repair equipment (it's called the "Horizon Machine") available. This equipment is supposed to be used to check for mechanical integrity, calibrate the display output, and talks to the processor and home button to make sure they work with each other. Sometimes when the connection is broken or a salvage home button is installed, Touch ID doesn't work and will require Apple's equipment to get it to work. In many cases an AASP only does a "repair" (even at a screen repair price) as a service replacement of the device. So it would be an equivalent device that may be new (unlikely with an iPhone 6s right now) or refurbished. The devices exchanged will become property of Apple and they will send them to a refurbishing facility and will place them back in circulation for future customers.

You can pay for a repair of the rear (facing you) glass.