What are possible reasons for the OP’s games to all be annulled?
The original question is a valid one, but if this is a troll, I’m not sure it’s worth continuing the discussion/contributing.
Is there somewhere that explains how OGS works in general that would include an explanation of “annuls”?
I find there are many things that the community knows about that don’t seem to be explicitly written anywhere. Annulments are one example. Ladders are another (not sure what their purpose is, nor how they work in the context of different game times).
Yes, this is quite unusual. I looked at about half of his games, and the only answer I can think of is that the OP is an alt sandbagger. Therefore, his wins were annulled because they were illegitimate. The unusual part is that the OP also threw some games (i.e., sandbagging by rank manipulation), so his losses were also annulled, because they too were illegitimate. It is unusual to see an alt sandbagger also engage in rank manipulation.
My site provides a very comprehensive exercise for all ranks, you may have a look. https://en.1200igo.com/beginnersquestion