My Hard Drive is dead! Please HELP!

Do you have any computer experiance?,

TRY EACH STEP IN ORDER TO SAVE TIME AND MONEY.
READ EVERYTHING FIRST BEFORE DOING ANYTHING.
BEFORE DOING ANY WORK INSIDE YOUR COMPUTER ENSURE IT IS SHUTDOWN AND UNPLUGGED, THIS IS IMPORTANT AND UNFORGIVING.

Have you tried entering the BIOS, Chipset Features to ensure the primary SATA drive is selected as the Primary Boot device?

Does the BIOS recognize the Primary Boot Device as your Hard Drive, there is (or should be) a function in the BIOS to automatically find all Drive devices installed.

Make sure you can access your machines BIOS, this is important. If you can not access the BIOS then it's not a Hard drive issue, it becomes a motherboard issue, try replacing the motherboard battery first thing.
Next  try removing the Memory cards and reinstall them one at a time, be sure to push the plastic locks on each side of the memory sockets outwards first, before removing the memory ( please do not force anything)
Observe the cutout slots in the cards and on the sockets, on the motherboard beside the memory sockets it will be marked 1 and 2,  reinstall one first, retry startng your computer, if it doesn't work then making sure to shut down machine, try the other memory card in slot 1, if that doesn't work, then making sure to shut down machine, replace te second memory card in slot 2, it's probably not a memory issue. There have been Boot Issues which ahve been attributed to poor connections of memory card contacts so make sure when the memory cards are removed and reinstalled Please, don't touch the electrical contactor surfaces, and install the memory card pushing down firmly ( but not forcefully), until the plastic locks on the side of the sockets flip back up and lock in the memory card into the socket. 



Before you go out and buy a new hard drive and afterwards find it doesn't work either, due to a power supply failure, you'll have to UNPLUG your machine, remove the side cover. There are Two connectors on the back of your hard drive and there should be two connectors on the back of the CD/DVD drive, these connectors have a wiring harness that is easily (visually) tracable back to either the motherboard or power supply, swap out the two smaller connectors that go to the power supply, there may be other unused small power supply connectors coming off of the power supply, try any addition small power supply connectors of the same size, configuration and with the same wire colours.(all of the small wiring connectors such be of the same wiring configuration). After swapping out the first one , RE ATTACH  the electrical outlet plug and retry Booting your machine, and then possibly the second connector, if that doesn't work, then at least you know it doesn't appear to be a power supply issue.

 If you know some one who does computer work in your area (reasonable price and reliable ) You could try having them place you harddrive into another machine  as a secondary drive, this will determine if you harddrive will work, can be accessed or if it is "BRICKED". (If you still have access to the internet, you can do a search for the term "Bricked" hard drive, it generally means a hard drive which is rendered either unaccessable or unusable. There are and have been thousands of others in your current situation, including myself)

Lastly
You will need to know the Manufacter of your Hard Drive, (Seagate, Western Digital or Toshiba )
You can do an internet search for HD Manufacters, but it all boils down to just three now.
Anyway once you identified the make and model of your drive, check the manufacters website for a Hard Drive firmware update. Seagate offers Seagate Tools which can be burned to a CD/DVD as a Bootable image to cheh the hard drive for issues and Firmware dowloads which can be burned to CD/DVD as an ISO Image (which is then Bootable), Western digital offers similar tools and downloads, all of which are generally free to download and use.

FIRST, MAKE SURE YOUR HARDRIVE IS ON THE LIST FOR A FIRMWARE UPDATE. Please don't try to update the firmware if your Hard drive is not listed, I have seen people who unintentionally destroyed their hard drives attempting un-necessary repairs, to find later it was a motherboard, power supply, memory or some other problem, some that could have been resolved faster and easier and less expensively. 
If your Hard drive is on a Firmware update list, then sometimes a "Bricked" hard drive has been restored to it's previous working order using the proper firmware update and procedures.

Do you know anyone who has a copy of the same operating system your using or has it installed on their computer? If so and you are using Windows, then have them burn a REPAIR DISK to CD/DVD, this should work on any machine using win 7, win 8 and it may let you know if you have a Hard Drive issue or something other.  Windows 7, Windows 8 (and Windows RT) include a built-in tool to create a USB recovery drive, so Repair Disk can be placed on a thumb drive, rather than burning a CD/DVD. Your system probably came with Windows 7 installed, but I don't know if you have upgraded to Windows 8 ( As for myself, I haven't upgraded to Win 8 yet, but I ditched the Acer Windows 7 Software Installation package for a Microsoft OEM Windows 7 Home Premium installation disk set to ensure I had a first qaulity Installation disk when or if needed )