Its really annoying that you are not able to see colors in pictures edited in the adobe photoshop trial, how are you suposed to try it out? you cant see what your doing? its way different than the real application and I dont like it. DUMB!
The trial application is exactly the same as the full version. It is fully functional and not limited in any way.
Are you seeing this behavior in all images or just one? Can you open an existing color image that woks fine elsewhere and open it in Photoshop and see whether that works.
Also let us know some details about your computer, OS so that folks can chip in and help you resolve the issue.
As has been stated, there is no such limitation in the trial version.
I suspect your computer is either at fault (e.g., your display driver may be faulty), or maybe it's something you're doing (such as choosing Grayscale when creating a new document).