IPhone – Can iPhone 4S’ digitizer be fixed

It's unlikely that the pixels have died, but the edge connector of the screen may have become dislodged or damaged, or it could be that the connection to the logic board could be loose.

You can try following this ifixit guide to see if taking it apart and reassembling it will restore any bad connections that dropping it may have caused.

If that doesn't work, you can just replace the display, as on pre iPhone 4 models the screen/digitiser and display are separate components, so if that's the only damaged component then it should fix the problem.

The digitiser is built into the glass with epoxy, so no, there is no way to separate it.

We tried. If you look at the lower left corner of the LCD you can see the scarring of our attempts to seperate the LCD from the digitizer.

^{Source: iFixit: Can I separate the glass from the LCD screen?}