There are three forms of wish sentences:

A)A wish about the present : it expresses a regret or dissatisfaction with a present situation.
   The past simple tense is used to make a wish for the present.

          I wish I had some money with me now.
          I wish my brother were here.

B)A wish about the past expresses regret or dissatisfaction about a past situation. The past perfect tense is used to make a wish for the past.

           I wish I had seen that film last week.
          I wish it hadn't rained so much when we were in England.

C)A wish about the future; it expresses a desire for change in the future.
   We use would+verb to make a wish for the future or to criticise or complain about someone's behaviour.

            I wish he would return the book he borrowed.
Note: would+verb cannot be used with the same object .
           I wish you would have a rest.
Note: If only can replace I wish to express a strong desire.
            I wish you would come with us= If only you would come with us.