Blown Power Supply by flicking voltage s

Hi there,

My little cousin was around the other day and flicked the voltage switch on the back of one of my PCs. The next day I turned it on not knowing this and BANG. It died.

Is there a way to get these repaired? Or should I go buy a new one? The only dodgy thing is it was a rather good one so I would like to repair it!!

By the way, its out of warrenty 🙁

Thanks