PROBLEMS

I'm having problems with the resolution of my textures. I changed the texture I was using and applied it to the whole terrain. I then realised that the resolution was bad, so i tried to change it back and the whole terrain went funny and didn't let me add any textures on it. I've tried to reload the terrain, generate surface texture, and refine texture tiles... don't know what to do...  Also, I restarted the terrain from scratch, which is really frustrating. I've posted on the forum but no one seems to be replying. This has been a problem before, but I thought I had fixed it by regenerating the surface of the textures. Any suggestions?