I had problems once and I think it was a problem with my internet provider. It eventually solved itself (from my point of view). I had to get in the habit for a while of copying every post I wrote so that if it didn't go through I could try again by just pasting it. That isn't a fix but it may be helpful to see if you can post something with several tries.
Someone I consider a master woodworker once told me that a master woodworker is not someone who never makes mistakes. He is someone who is able to cover them up so that no one can tell.