Computer will not boot up

During the night my pc started to make a mechanical clicking noise. I shut it down and went back to sleep. The next morning it would not come on. The on button lights and the mother board light comes on. The fans will not run and the power supply test botton does not do anything. There is a green LED light beside the test button and it does not come on. What do think?

Possible failed PSU.......Are you able to test with another 'known working' Power supply?

Regards

No. Are PSU very expensive and would Walmart or Radio Shack be a source to purchase one?

What about ebay?

http://computers.search.ebay.com/power-supply_Computers-Networking_W0QQcatrefZC6QQfromZR4QQsacatZ58058

Thanks I'll try ebay