how to fix one loose tile

We had a significant leak from our bathroom sink a couple of weeks ago. the leak is now fixed but one of the tiles directly above the sink and cut with a curve to fix exactly the curve of the sink is coming loose, grout is coming away.

Could someone advise how to re-fix it without damaging any others?

Thanks for your help.

You'd remove the tile, clean all adhesive and grout from it and the wall behind. Then once the wall is fully dry and clean of all debris, apply some adhesive and replace the tile and grout once set. Depending on how long the other tiles are there, you may have difficulty matching the grout colour though.
Leo

Thank you Leo, much appreciated.

IF u dont have adhesive a no more nails or even silicon will do the job