USB drive not recognized in Linux

This requires kernel modules to be loaded which perhaps are not loaded by default.
Add the following modules to your /etc/modules file so they will be loaded at boot:

ohci_hcd
usb_storage
sd_mod 

If you just want to test only the functionality you may manually load the modules from the command line:

modprobe ohci_hcd usb_storage sd_mod

With the 'dmesg' command you become some informative output regarding the discovery of your USB hardware.
If your usb drive is connected you should see devices in the "/dev/" directory that begin with "sd":

# ls /dev | grep sd
sda
sda1

Mount the drive to a mount point of your choice, in following case a directory called "usb" in "/mnt":

cd /mnt
mkdir usb
mount /dev/sda1 /mnt/usb

If the usb drive is FAT formatted drive you may need to do the following:

mount -t vfat /dev/sda1 /mnt -o iocharset=cp437