This sentence expresses the wish apposite present fact.I wish I knew how to drive.
So I don't know how to drive in truth.
This means "I'm sorry that I don't know how to drive".
This sentence expresses the wish aposite the past fact.I wish I hadn't made such a mistake.
So I made such a mistake in truth.
This means "I'm sorry that I made such a mistake."
If ~ the past,
should + R
(if we use 'be'verb, we should use 'were' )
If ~ the past perfect,
should + have +p.p
We usually use 'form 1.' to express a wish apposite present fact.
And we usually use 'form 2.' to express a wish aposite the past fact.
So, wish is used when we be sorry or regret the past and present things.
'Neung-Yule Basic English' has these sentences.