Ignoramus15467 wrote:
In our basement shower, several tiles fell off. Behind them is
drywall. The tiles are not broken and I would prefer to just glue them
back in if possible. What glue and process would you recommend.

You would be wasting your time and effort, not to mention throwing good
money after bad.

Your shower has a terminal problem and you need to amputate that
drywall to save it.

R