Your second sentence is the correct one because you are expressing an "impossibility," loosely speaking. IOW, you would have given an answer IF you had been allowed to do so, but you weren't--so you didn't!
The subjunctive mood (or mode) has fallen on hard times in recent years, but I think its use is still valuable in making clear the distinction between something which is in the realm of impossibility ("If wishes were horses, [then] beggars would ride") and something which is not ("If I was ready back then [which I was], then I'm even more ready now").
You can complicate (unnecessarily) your option two by adding a few words to it:
If I were to have had enough reputation . . .,
which has you looking back in time instead of to the future, which "were I to have" communicates.
The same goes for your option number four, with the addition of the word had after the word have.
Option number four, by the way, is "correct" only when the wished-for action is yet future, not in the past.
I suppose option number one could be "correct" in a very rare situation, as when a person uses the words to ask a question about whether he was or was not allowed to do something:
Was I to have enough reputation in order to participate [or to have participated] in said activity?
The same applies to option three, if you expand it and frame it as a question:
You mean to tell me, if I had enough reputation I would have been able to participate?