There are certain times that words fail me. Some experiences can make you feel such strong emotions that, as the cliche goes, words cannot express.
What I have found about those experiences is that they usually involve aspects that are deeply rooted within you. Imagine some item of great sentimental value, something that you have had with you for years and that you treasure. If it breaks or gets lost, you didn't lose a thing, you lost a part of yourself. You've lost your heart and soul, along with your peace of mind. Such a less is devastating and can be emotionally crippling.
But if you ever tried to describe how you felt when you experienced such a powerful sorrow or a similar joy (like finding that object was not lost but misplaced and you found it during your grieving), you will find that you simply cannot capture the feeling.
Truly, I do not it is possible to describe such a feeling with words. You can, however, create such a feeling. Consider a character with a sentimental object. Talk about the item early on. Show the attachment to it. Don't prattle on about it, but show how it is always there and how it makes the owner feel. The reader will make the same connection to the item. When the character loses that item, the reader will feel the same loss. When you describe what the character does following the loss, the reader will understand, and will also feel the same kind of loss, depending on how strong a connection they've made with your character.
Words aren't everything, but sometimes they're all you have. Use them the best that you can.