Chosen Solution
I checked if it’s hidden but it’s not. It’s not in the sidebar too. My Samsung G2 Portable external hard drive lights up and starts with a typical sound when you plug an external hard drive to a computer. If I can remember I didn’t drop it or anything but I think my macbook pro automatically forced eject it. I tried plugging it on different macbook/iMacs or even PC computer.
Go to Disk Utility and verify the drive shows up in the left hand column. If it does, it should show the size and manufacture of the drive on one line, than indented below it should show the logical name. Click on the drive and select repair. It will scan the disk and attempt to repair it if errors are found. If they are found, run repair one more time to see if any errors remain. If so, the disk may be going bad.
Go under the finder to preferences - General and turn on external drives.
