I have a SanDisk flash drive (8 gig) that I cannot seem to figure out. When I plug it into my PC via USB, it says it's completely empty. Nothing on it. Yet, when I click on properties, used space shows 7 gigs and free space shows only 2 MB.

Note: I used this flash drive as a hard drive for my Xbox 360 a while ago, and the Xbox formatted it to be able to work with the Xbox.

I guess I need to format it (thus wiping it) but I don't know how to do that.

which operating system your using will be important, if it's windows 7, XP, or vista this guide should be helpful

up your start menu, right click [My] Computer, click on Manage, in the window that pops up look for Disk Management in the left pane, that will bring up a list of your hard drives, disk drives, and flash drives

in the bottom half of the middle pane look for your flash drive and make sure it's all one partition, if it isn't, then you'll need to delete those partitions to remake it into a single partition

once/if it's one partition, right click it and select format, i think at 8 gigabytes, you'll need to use the FAT32 or NTFS, use the default allocation size, and i recommend leaving the quick format off

I'm using Win8, and I actually just figured it out. It was absurdly simple. I just right clicked the E drive and it said "Format", I clicked it, and put it to FAT32 and did the default allocation size, and it was done in less than a second.