Brand new to Apple products.I have used and repaired Windows for 25+ years but some one recently gave me a Mac that needs restoring and I can't figure out where to get software. There are no restore places on the computer. When I am under utilities screen and click on recover OS I get message that the server cannot be contacted. I can't get it from Apple website as it only available to Apple computers. The OS on the computer is High Sierra. If a person had to replace a bad HD what would they do to reload system