Open up the machine and sniff the PSU. If it smells bad, its gone. Get a new PSU and verify the diagnosis. If the computer doesn't turn on, then your mobo could be fried. We'll come to how to deal with that later. Just check the PSU now.
As a precaution, ensure the wall outlet is of the proper voltage and the earthing is done properly. Also, keep the area well ventilated and away from moisture.
goldeagle2005
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I'm guessing from your discription that this is an older machine, if this is the case and it smoked, it may not be worth investing in.
dcc
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