pc not starting

Oct 21, 2018
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i know little to nothing about computers, i got a pc a few years ago it was built for me by a friend of mine and i left it for about 6 months and when i came back to it the power light would come on but when i pushed the on button the front two fans would twirl for about 5 seconds and the back one wont spin at all. any info on what i can do??