Recovery Mode and Internet Recovery Mode doesn't work.

Saikhan95 wrote:

Hi! I have mid 2011 21.5 inch IMac. I want to reinstall MacOS High Sierra (I know that my IMac supports it) and Erase all data on my Macintosh HD. But the problem is that Recovery Mode doesn't work. It's just infinitely loading. Internet Recovery Mode doesn't work as well. The globe is spinning, but some time later error symbol pops up and that's it.

If the iMac was connecting to the Internet via Wi-Fi before you erased the macOS?

Try plugging it directly into your Router with an Ethernet cable.

How can i reinstall MacOS and erase all data on my HDD?

Have a look at > How to reinstall macOS from macOS Recovery - Apple Support

I downloaded MacOS High Sierra on my USB driver, tried to start up IMac, hold option/alt key, but it's doesn't show my USB driver, from which i can install High Sierra. Am i doing something wrong?

I use DiskMakerX to make a bootable installers, see > https://diskmakerx.com/download/

lso i have USB to SATA cable, which helps me to connect Macintosh HD to my windows PC. I'm thinking that i can erase all data on it through my windows PC. Correct me if i'm wrong.

You might, but then you are still stuck, trying to format and install macOS.

You'd something else to wipe the Mac.

Does the Mac boot to an OS at all?