Q: Seagate External Hard Drive//Not Showing

Recently I purchased a Portable Seagate 2TB External Hard Drive for my MacBook Air. I have put all my movies, music, documents ext onto my hard drive along with my important homework. The reason I did this was to reset my mac and then return all my old documents, photos ext, back to their original place. I was successful in doing so and freed up a lot of space. A couple of days afterwards my MacBook fell asleep with the external hard drive still connected and now the hard drive no longer shows on the desktop or in finder. I am able to find it in my "Disk Utility" but for some reason it shows the hard drive faded grey and full? I have tried connecting with different cables and on different devices as well. Also performed the first aid option in "Disk Utility" with no further result. I have contacted apple support and discovered it was the external hard drive with the problem so they could not help me. They then redirected me to Seagate Support, and I had already tried the methods they gave me (listed above). I am wondering if anyone here on the Apple Communities has experienced the same problem as me, it would be much appreciated any advice you may have. I have important files that I need to recover.

PLEASE HELP!!!