You will have to be a lot more descriptive than that.
1) does the BIOS see the drive? (see manufactures site about accessing and changing BIOS settings)
2)Does disk management see the drive? (Right click My Computer, Select Manage, Click Disk Management) If you see your LG HXD2, right click and select assign drive letter. now pick a letter and say okay.
if that doesnt help, you'll need to post more information. for instance, what ur seeing / not seeing / whats happening / not happening.