I was given a mobile phone, my first smartphone, with a case and a
protective glass plate on top of the screen which got water under it so I
carefully peeled the glass protective plate off.

The "glue" is only on the top and bottom of the 6 inch long phone.

What glue is it?
When I removed the protective glass using my fingernail to peel it off
gently, I let it dry which solved the water under the glass problem (and
the water inside the protective glass made a fog like that inside of a
double pane window that cleared up after leaving the glass in the sun for a
day).

The glue is no longer sticky at the top and bottom
What glue can I use to put the glass back on and have it stay on normally?