There are some great answers on the linked duplicate. Also interesting to note is that subjunctive is much more common in American English than in British English.
– Kit Z. FoxDec 14 '15 at 18:47
Mostly you find: I wish I were* dead (were* subjunctive) / I wish father were* here. - The subjunctive can be replaced by "was" as a substitute of the subjunctive. In the subclause you can also use "would": I wish you wouldn't smoke. Or "could": I wish I could swim.
– rogermueDec 16 '15 at 06:26