Technically, "I wish I were special" (the pronoun "I" is always written in upper case, "i" is wrong) is the correct way, although "I wish I was special" is so widely used nowadays that it's generally considered acceptable. "Were", in this case, is the past subjunctive of the verb "to be" ("ojalá fuera especial"), but because of its similarity to the indicative plural past tense of the verb ("we were", "you were", "they were"), it is often re-analysed as a past indicative form and "corrected" to the singular "was" (literally "ojalá fui especial"). When speaking or writing in formal settings, I would recommend using "were", but otherwise you can use either form.

Nowadays, both forms are considered correct. The 'were' version is the technically more correct form, and that is the one you will find in textbooks. However, the 'was' form has become so widespread that it is now quite acceptable in all but the most formal of situations. Twenty or thirty years ago, 'was' was considered incorrect, but this is no longer the case. I am an examiner, and the exam board I work with accepts both forms as correct, even on English language papers testing grammar.

Both are correct.

thanks for your answers and corrections :D

I agree with the answer submitted by Coligno, though i would suggest you use "were" because it is the more correct form.