Samsung 2TB SSD T3 does not mount

Hello,

My external 2TB SSD drive does not mount properly, but shows as a 128GB drive.

I bought a Samsung 2GB SSD T3 drive to back-up photos. After a back-up of my Aperture library, all seemed to work fine. I thought I wanted to open it in Photos.. ..that took a very log time and after an hour the percentage complete was still 0%. Could not stop the process so forced Photos to stop and ejected the SSD drive. Obviously something went wrong when I did so and I can now not get it to work again.

Disk Utility can see a 131GB drive, but I can not format or change anything.

Grateful for support!

Torbjorn

P.S. I am running a Macbook 12" retina late 2015 and latest 10.11.6 OSX