WISH

The verb to wish is followed by an 'unreal' past tense when we want to talk about situations in the present that we are not happy about but cannot change:

* I wish I had more money (=but I haven't)
* She wishes she was beautiful (= but she's not)
* We wish we could come to your party (but we can't)

When we want to talk about situations in the past that we are not happy about or actions that we regret, we use the verb to wish followed by the past perfect:

* I wish I hadn't said that (= but I did)
* He wishes he hadn't bought the car (= but he did buy it.)
* I wish I had taken that job in New York (= but I didn't, so I'm stuck in Bristol)

NOTE: When we want to talk about situations we are not happy about and where we want someone else to change them, we use to wish followed by would + infinitive:

* I wish he would stop smoking. (= I don't like it, I want him to change it)
* I wish you would go away. (= I don't want you here, I want you to take some action)
* I wish you wouldn't squeeze the toothpaste from the middle! (= I want you to change your habits.)

(from Online English Grammar)

Exercises 1

Exercises 2