What’s happened to my html programming?

I am suddendly unable to write html into my web pages. When I do there is no change. Same thing with my mail. I am able to change the size of the text but not colour. I have used hex codes and colour names to no avail. The problem seems to be only with the colour. It was fine a few days ago. On the tools menu I changed the text to html (in my mail) – still no effect.Is there any way I can restore my system and settings to the original? My OP program is XP. Thanks. Sue