black taxiway signs

Trying to help out a friend here. He and a couple of his friends did something to fs9 while cleaning out what they thought were unneeded scenery files and now all their taxiway and runway signs are completely black on both sides. I am a novice with scenery files but I am thinking that somehow they deleted some sort of texture file or something that contains the characters and background colors use on these signs. Can someone help me get him back into the game? Are there specific texture or other files that are used to label these signs and if so what are the file names so that I can find them on my fs9 discs and direct them on reinstalling them?Any help greatly appreciated.Dan