Which is correct english?

*Sorry if this is in the wrong forum and I just noticed the title doesn't make sense at all :S*

On an advert it says 'wishes she were blonde'. I was talking to my family about this for ages and ages because my mum says it should be 'wishes she WAS blonde'. What is the diference, where should it be WERE and where should it be WAS? It may seem a stupid question but I've been puzzling over it for ages...

Was - is past tense 1st or 3rd person singular of 'Be'
Were - is past tense plural of 'Be'

'I wish I was...'
'I wish you were...'

Heh - She were in the bath - is incorrect in past tense, it should be she was in the bath. But she wishes she were in the bath is correct, because it's not something that actually happened and is wishing it in the present tense - therefore, all above posts that conjugate the word are invalid - as the writing is in present, and not past tense! Wishes she were blonde is correct. . . It's just a little old fashioned - I mean, just think about how much the Englsih language has changed, we don't still say things like thee, thy and thou - but that doesn't mean it's incorrect to say them. Perhaps in a few years, people will be questioning whether isn't it shoult actually be innit . . . :S I dearly hope not . . .

Peace. [Sole]

Thanks to all who answered, I think I understand now =D
Polly x