After "wish", we use the past subjunctive to express a wish about the present (be = were for all persons. Was can be used in informal speech).
I wish Mom were here now.
I wish I had a car.
To express a wish about the past, the past perfect subjunctive is used after wish.
I wish I had gone to bed earlier yesterday.
I wish I had been born in the U.S.
Wish is also used as "please" followed by would.
I wish you wouldn �t make so much noise.