Try attaching the external drive to another computer to see if it works on that one to rule out damage to the drive itself.Some imported drives come completely empty, and while macOS should detect and offer to format them, it doesn’t always work. Make sure the drive has been formatted.Reboot your Mac to see if it was an open program or app stopping the drive from being detected.Try a different wall outlet if there is one nearby.Change the hard drive power cable if you have a spare.Check the condition of the cable and swap it if you have a spare.Check that the external hard drive has power if it needs it.
After all, no one wants to waste half a day because they didn’t realize something just wasn’t plugged in properly. Get into the habit of doing this with any computer issues, as it can save time, money, and hassle in the long run.
