New to notepad++...why has my text suddenly become all red with green highlighting?

[NikCs2015]

I was writing nice notes my comments appeared in green when preceeded by a #. now all of a sudden that is not happening and any text I now write is all one colour (red) with a light mint green highlighting? anybody know how I can change this back?

[Claudia Frank]

Hello NikCs2015,

it sounds that either the file extension is known by a lexer and does automatic coloring
or you did some changes in styler configurator (settings menu).

Cheers
Claudia