Q: Seagate Backup Plus Slim Won't Appear on Mac

- Is the drive self-powered, that only powered by the USB bus? If so it could be that the USB port does not provided enough power. You can try a powered USB hub. You can also get a USB pigtail that takes power from to USB ports to the single USB port on the drive.

- Does it show in Disk Utility?

- Does it show in System Profiler under USB? You should see the chipset in the enclosure as well as the HD itself

OS X: About System Information and System Profiler - Apple Support

- Is the disk show when connect to another computer?

- Can you hear/feel it spinning? Do the light on the drive light?

Likely a lack of power.

laura1475 wrote:

 

I recently purchased a Seagate Backup Plus Slim because I had to reset my computer. I transferred all of my files onto the drive and it was fine.

 

I just went to take all of my files off the drive and back onto my laptop and the drive won't appear anywhere. I'm terrified that all of my files are going to be lost forever. PLEASE HELP!

Try powering off  your laptop - wait a minute - power back on then hook the drive up again.   Worked for me with a drive I dismounted and unplugged so I could use the USB port -- would not show again until I had shutdown and powered up.

Maybe this. It depends upon the port on the drive:

StarTech.com® 1' USB Y Male To Micro-B Male Cable For External Hard Drive, Black