Currently Being ModeratedApr 9, 2013 12:26 PM (in response to dwf1)
Restart and hold the command and r keys (both keys together) down till you see the Apple logo. Select Disk Utility and hit Return.
In DU, select your hard drive, and run Repair Disk. When that is done, quit DU and restart.
Currently Being ModeratedApr 10, 2013 12:16 AM (in response to Eustace Mendis)
Hi Eustace Mendis,
DU told me that my Hard Drive is okay but after the restart the same problem (checkered screen with Apple Logo) appeared so I restarted with command/r again and am now changing to my backup form timemaschine.
This will take 28 hours I'll post if this will bring my iMac back.