I have a Kingston 32 Gigabyte USB flash drive that is detected in the Disks program but not showing up in the Files program.
In the Disks program, what is the partitioning scheme for your flash drive?
Usually it is a single partition if FAT32 type. If it is any different, please comment. Note down the device name for the partition (Example: `/dev/sdb1')
Follow these procedures in a terminal:
sudo mkdir flashdrive
sudo mount /dev/sdb1 flashdrive
cd flashdrive && ls-ltr
The contents of your drive should be listed by now. Most likely, Nautilus will also show your usb drive. To manually unmount the drive, follow these step in a terminal:
sudo umount /dev/sdb1
sudo rm flashdrive -r
The problem appears to be that the system isn't automatically mounting the dive. If you have any problem following this solution, leave a comment. You can also create a script to do all this job automatically.
Is the USB specifically not getting detected in Ubuntu 15.10 ? Have you tried plugging it in to other systems ? And did you remove it mid-way while formatting ?
If its a pen-drive problem and supposing you are not concerned about the data on the stick then you can use gParted.
Installation Guide : http://ubuntuguide.net/install-graphical-partition-editor-gpartedin-ubuntu-linux
After installing , launch gparted from the terminal. On the top right corner select your pen-drive /dev/sdb1 and create a partition table. That should do it.