in reply to character replace

First you will need to define what the difference is between "the character '&'" and "the entities". Then you will need to write a regular expression that replaces "the character '&'" but not "the entities".

Of you're talking about HTML, consider the following cases:

Meier &Cie Muller & Co Dowe, Cheatham &Howe, Attorneys Wallpapers&Paint;