Thinset removal

Help! I have several broken ceramic tiles I need to replace. I can't use a machine to remove the thinset and risk damaging the adjoining tiles. Is there a tool I can use that will not cause damage to adjoining tiles?

I can't use a machine to remove the thinset

Do you mean "remove the grout" between the tiles? A utility knife or a hand-held grout saw will do that.

I was able to remove the grout between the tiles, but what was underneath the old tiles was a substance like thinset. What tool would I use to remove the thinset so I can put another tile down.

Usually a scraper or grinder or belt sander or chisel and hammer will remove the thinset. More importantly is: "Why did the tiles break to begin with?" Are the tiles below broken also?