grammar question, future condition looking back on past?

Question

okay, here's 2 variants, tell me which variant is grammatically better and what is wrong with the other (if anything) or if nothing is wrong, why did you make your choice..
(1)if i were there, i could have done it
(2)if i had been there, i could have done it
if i were there, i would have done it
if i had been there, i would have done it

Answer 1

"If I were there" suggests the present tense, meaning if I were there now.

"If I had been there" means in the past.

So the preferred choice depends on whether you mean being there now, or in the past. From the rest of the sentence, it sounds like you mean in the past.

How about this: Had I been there, I would have done it.