Hi Amal...It sounds to me that your son has developed a fear of springboard diving (the blind dives) and in order to be successful as a diver, he's obviously going to have to overcome that fear. One way of doing this (and I've suggested it in the past to other parents who have experienced similar situations with their children in various sports) is to have your son begin visualizing himself doing those blind dives, over and over again. If fact, if you should have some videotape of him doing those dives, I would recommend transferring them to a video and adding a musical sound track with lyrics that have specific meaning for him and have him watch the video over and over again as he listens to the music...then, when he gets back into a swimming meet and is about to compete, he would then listen to the music track on a Sony walkman or some other type of playback device and when he listens to the music it will re-create the images from the video tape. Let me say outright that this will defintely work; however, an important ingredient is your son't belief that it will work...because if he doesn't believe it will work, it won't.
Hope this has been of some help. Visualization is a powerful tool for athletes to use since the brain cannot differentiate between that which you actually experience and that which you visualize.