so my new sata HD wasn't working so I tried a few things and eventually I took the cord that connects the HD to the motherboard out of the plugin in the motherboard and put it in the other plugin and it worked for a few days. Then it randomly stopped working, so i plugged it back in the original plugin and it worked. a day later it doesn't work in either slots in the motherboard. I even tried a different cord but that didn't help. what would be the problem?
so my new sata HD wasn't working so I tried a few things and eventually I took the cord that connects the HD to the motherboard out of the plugin in the motherboard and put it in the other plugin and it worked for a few days. Then it randomly stopped working, so i plugged it back in the original plugin and it worked. a day later it doesn't work in either slots in the motherboard. I even tried a different cord but that didn't help. what could be the problem? thanks.

It sounds like you have a bad hd. Take it back and tell them that you'd like to swap that hd for another one, and explain to them the problem you're having, and what you've tried to remedy the situation..

If you can temporarily afford it, go buy a hd, save the receipt, test it out on your computer, and if it works fine, then your hd from your new computer is probably bad.

As long as you save your receipt and have the original packaging (even the plastic), you can take your hd back within 30 days and get a refund.

There is a major department store that allows it, and I've done it on numerous occasions when I needed to troubleshoot problems I had on my computer. It will definitely save you a troubleshooting bill if you were thing of taking it in to a repair shop.