I have been using my windows 8 custom pc for approximately 6 months with absolutely no problems, until today. I left my computer on for about an hour while I was gone, and when I returned, realized that there was a reboot or insert boot device to continue screen. After asking around, I learned that my sibling had noticed the computer frozen in the login screen, and then held down the power button. when he turned it back on, the computer could not read the hhd. Im afraid it may be damaged, as I have checked the inside of the case to confirm if it was connected and went into the BIOS to further confirm that the HHD still could not be read. please help!
If the HDD isn't being detected at the BIOS level, and you're sure that there are no bad connections, then I'd say it's time to start looking for a new hard drive. I'd definitely try it in another system first if possible, though, since if your power supply voltage somehow became unstable, a lot of new(er) drives will detect that as a failure and refuse any drive access requests. If it does, then something might have gone wrong with the SATA controller on your motherboard.
I'd say that the system freeze was caused by the drive failing - modern drives likely won't be damaged by an unexpected shutdown. That's just my opinion based on the information you've given.
EDIT: I almost forgot. Before you try replacing anything, reset your BIOS by clearing the CMOS on your system. There should be either a jumper or button on your motherboard that will do this... I'm sure the documentation can tell you where it is. If you can't find that, you can accomplish the same thing by unplugging the system, removing the small battery cell on the motherboard, and holding down the power button for a few seconds. Doing this will clear all of your BIOS settings, so be prepared to re-enter the time, date, and anything else you changed manually back into the BIOS. It may sound strange, but this has fixed a lot of problems when something strange goes wrong out of nowhere, and is generally the first thing I try since it's fairly easy to do.
Thank you for the advice! when I reset the BIOS, the HHD was once again detected! However, just out of curiosity, If the HHD had to be replaced, would I still be able to use my OS instillation disk on the new HHD/SSD?
If this is an OEM disc, the only time you might have 'trouble' is on a new motherboard, though I've never had any problems myself and I'm told that Microsoft's support will clear that up pretty quickly. So, yes, you should be able to reinstall Windows with no problems. If it's a full retail disc, then you're good to install on whatever you want.
Glad to hear it worked! A hard power-down can cause that sometimes. Best of luck in the future!