Specifically, this question on Value of Money. I put a comment on the Question itself (two, actually, one in response to another person). All three comments are gone - any reason why? Alternately, is there any way to find out, other than posting here?
I deleted it and the followups as it was an answer as a comment: Should answers be left in the comments?
In general comments should be seen as temporary notes on questions only, not anything that can be expected to last long term.
Sometimes if a question isn't already answered well, I would leave a partial answer in a comment alone to see if it helped produce good answers, but this question already had several answers
In this case I acted in response to a flag from a user, but I'd probably have done so anyway if I'd come across it directly.