I know how that feels.
This year, I've been able to cry. Once last spring, I went for a nighttime walk in the cold and ended up laying on the walkpath (out where no one was around) crying my heart out. My walk that night started with rage at my wife for triggering me. After being out the better part of an hour, the rage became frustration and finally, full on grief. I have not been that low since I was 18, which was quite some time ago.
I recently went on a wilderness vision quest where I cried several times, but those times were mostly tears of joy. Hmmm..."joy" may not be the right word. Let's try "understanding".
I don't have any advice on what to do, except maybe to suggest going somewhere very far away from anyone. Maybe the isolation might help. After all, we are very isolated at times, even though there are always people around. Maybe really being alone will help the feelings come.