I am certain that another user could explain this better (so please chime in!) but i believe this issue
is caused by having changed your user name from the original name that you signed up with.
You may need to change it back to that name in order to leave comments again.

Unfortunately the ability to upload user icons has been broken now for many years.
Those of us that still have our icons have them because we never tried to reupload
or change them before the function broke and they are from a long time ago . . .

This site has been broken for a long time.
Its very sad, and there is no real chance that these things will ever be fixed.
I am still however dedicated to it even in its broken state <3

Anyway, i hope you get your issues resolved!

Ohh good!
That is fantastic news : }