If you run "dmesg" in a console you can look for lines like this:

USB Mass Storage support registered.
hub.c: new USB device 00:10.0-2, assigned address 5
scsi1 : SCSI emulation for USB Mass Storage devices
Vendor: FUJITSU Model: MHJ2181AT Rev: 0811
Type: Direct-Access ANSI SCSI revision: 02
Attached scsi disk sda at scsi1, channel 0, id 0, lun 0
SCSI device sda: 35433216 512-byte hdwr sectors (18142 MB)
sda: sda1 sda2 < sda5 sda6 > sda4
WARNING: USB Mass Storage data integrity not assured
USB Mass Storage device found at 5

To see if your drive has been found. You can then mount it yourself with mount /dev/sda6 /mnt/sda6 (tho with the number of the partition you want).
I had a problem lately where the ehcd-hcd module was preventing my usb drive from working. You can try removing that module with rmmod ehcd-hcd and disconnect and reconnect your usb drive and see if it was found.