iMac won't start after attempted reinstall of OS

My 2009 27" iMac will not boot up. I was trying to wipe and reinstall the operating system (mountain lion) but it ask for a CD which I didn't have, so I turned it off meaning to try again later.

When I turned it back on, it no longer returns to the install prompt, just the greyed out no entry symbol.

I tried putting a Snow Leopard CD in but it had no effect and the CD is stuck inside now.

I've also tried holding down some key combinations I googled, but those had no effect either.

Any idea what I can do about this?
Thanks

Reboot it and hold down the Command and the R keys at the same time. Does it boot to the Recovery partition?

chscag said:

Reboot it and hold down the Command and the R keys at the same time. Does it boot to the Recovery partition?

Click to expand...

OK I just tried it. No, nothing happens it just goes back to the greyed out no entry sign.

The hard drive must have been wiped if you can't access the Recovery partition. Either that, or you have a defective hard drive. The first thing you need to do is get the Snow Leopard DVD to eject. Try rebooting and hold down your mouse button at the same time. The disk should eject.

Once you get the Snow Leopard DVD out and if the optical drive is working OK, you can try booting the machine with it. Hold down the option key as soon as you hear the boot sound - then select the DVD to boot from. Let us know if that works.