I lost the OS for the iMac 2011 27inch disk. Is there a way to get a replacement

ezymel wrote:

I used to have the iMac 2011 27 inch OS but I am unable to find it. Can I get a replacement for it?

Do you need it? You can use MacOS Recovery to reinstall the OS if you need to. I presume you also have High Sierra on your iMac - which is as far as it can be upgraded. If not, High Sierra is available from the App Store at this link.

To answer your question more directly, the answer is no, not from Apple, but you might find a disc on an Internet marketplace. However, given its age and the limitation often placed on install dates in OS installers it might not work anyway.

The modern replacement is a bootable USB installer. If your 2011 can't boot you can make a bootable USB installer using another Mac with a model year between Late 2009 and Mid 2017.

Create a bootable installer - Apple Support

ezymel wrote:

I used to have the iMac 2011 27 inch OS ...

To be clear, do you mean its original System Install DVD?

Apple no longer provides replacement discs, but please write back with clarification. The ability to reinstall macOS from Recovery is gone.