The value of silent support is immense. Imagine the example of a funeral. The widow and closest surviving family members are experiencing extreme loss and incredible heartache. There are no words that will take their pain away. We need not try. We need not fill silence.
Yet those suffering the most do need to feel supported and surrounded by support and knowledge that they are not alone. They need to feel that it is okay if they do not feel they have sufficient strength. The presence of those that care for them is uplifting and powerful. It is in many times all that is necessary.
If you see someone in a particularly heartbreaking situation that you cannot fix, consider just giving them a hug; just holding them for two minutes straight, without saying a word. We all know actions speak louder than words. Your presence is powerful. Embrace it and do not let words get in the way.