In some, not all, text boxes, such as search, I can't see what I typed until I tab out or if I highlight the box. It seems that the text is white and so disappears in a white box.
In Firefox I checked and my settings for text are black, not white. Advanced Appearance Settings has text in the Message Box as black.
It just happened, out of the blue, I can't find when it happened to successfully Restore.
In this forum's Search, text is white but a lower box where you put in words to search by has a pale blue setting and so the words are visible. In My Yahoo's Search box in the middle the box comes up green and so the words are visible.
About the same time, my My Yahoo page, which had had a blue background, turned to white and I had trouble resetting and saving a colored theme. The next day the trouble was gone.
One new thing was that I started trying to use Gmail and it was a basic white background but that has been fixed.