Chosen Solution
This is very detailed, please read careully. I tore down my late 2008 iMac, & installed a new video card. I hope we put it back together right because it had been several months since I had started it. We put it back together & initially received a question mark at start up. A little later there was a pop up askinng if I waned to start from back up disk or download Yosemite again. It won’t let me do either because it can’t find the hard drive. I installed a brand new hard drive 6 months ago. So what did we do wrong putting it back toether, if anythng? My son helped & was a real pain in the butt! We even have screws leftover. Incidentally, my iMac is allowing me to get to this forum. My acccount is lady_cerridwyn, can’t remember log in.
So what i can tell from reading this is one of the cables to the hard drive is either disconnected or your having other issues with the hard drive. Im a little confused though as you said you where able to load up the site. What operating system are you using to do so? Are you able to boot off an external drive? if so, Open Disk Utility and check to see if the system recognizes your HD. If not. Disassemble the iMac and check the cables going from the drive to the motherboard. I like to check these iMacs with the LCD on and the aluminum housing off before i reassemble just to be 100% sure.
