shaps

Forgot to say that I need to build the wall up behind the tiles so they become flush with the others.

Hi can anyone offer advice on the best way to reattach four fallen bathroom tiles? Initially, there were a couple of loose tiles separating from the wall. When I tried to check them, two more tiles came off with what looks like some of the wall , exposing some bare brick behind them. It seems like water has been getting behind the tiles for some time damaging the material between the wall and the tile . Does anyone have suggestions on how to reattach the tiles and repair the wall ? The rest of the tiles are secure and show no signs of movement. Any advice would be much appreciated