First time building: usb ports and video out not working

Urrrhuh

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Nov 18, 2011
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So i was building a computer for the first time, following the newegg tutorial video.
I built the system outside the case to see if it worked, and it did.
After building it inside the case, i discovered the video out no longer worked (the one on the motherboard)
ALSO, the usb ports wouldn't detect my mouse either.

I had to use the video port on my graphics card, and the front panel usb ports.
My guess is that none of the back ports on my motherboard are working.

What did i do? And how do i fix this ><"