iMac won't start

My iMac was hung up on the desktop. Nothing worked, keyboard, mouse

I rebooted with the power button now all I hear is the DVD drive and what sounds like a clicky hard drive.

Black screen nothing works

Repeated restarts, no chime just dvd running and funny Hard drive sound (grinding)

Thanks

You should give us the specs for your iMac. What year and model do you have and which version of OS X are you running?

As far as the problem with your iMac not starting, it sounds like the hard drive has failed. It's likely you'll need to replace it. Have you been making backups?

21 inch iMac
iMac, OS X Mountain Lion (10.8), 2.66GHz Intel Core 2 Duo 8 GB ram

I backup regular and use an external hard drive for all my audio as this is my music computer in my recording studio

It has been a work horse so I figured it was the hard drive.

Boot into Recovery mode and check the hard drive using Repair Disk in Utilities, as it may have failed. How to use Recovery:-

http://support.apple.com/kb/HT4718