Mine, in essence, lasted for years. However, don't be discouraged. I might not be the norm. All I know is that emotions were dangerous, I was not allowed to express them, both in childhood and in adulthood, so I just went flat. People shut me down, because they could not deal with my anger or my tears, before I finally shut down as my only option for survival.
The damn broke and water gushed out finally when my father died. I sobbed and sobbed. Again, no one could deal with my emotions. None the less, that time I could not shut them down. I even got kicked out of a church for being "disruptive." I tried my best to cry quietly in the next church I joined. And the one after that, which is the one I am in now, years later. Sometimes I cry a little, silently, just a few tears these days. At least I am no longer in the "flats!" What a relief, I can express myself.
I paint paintings a lot now, to express my feelings. I have a job now, which I did not back then. I have had it for over a year. I'm doing DBT and Trauma Based CBT with my T. and here on these forums with an email group. These help a lot too.