1TB Seagate Passport USB drive not showing up in my computer

I bought a 1TB Seagate passport then right after buying it I had to use it to back up my girlfriend’s computer, which happens to be a mac. So everything went well for my girlfriend but now when I plug the Passport into my windows 7 computer it does not show up in my computer. Then I downloaded swiss knife and tried to format the Passport. No such luck, swiss knife always gives me a Read/Write error. When I try to use the Win 7 disk manager program all I can do is convert the Passport to a dynamic volume but I can see the Passport in both disk manger and swiss knife


Here is my speccy summary with the info on the hard drive:

Operating System

Microsoft Windows 7 Home Premium 64-bit SP1

CPU

Intel Core i7 3770 @ 3.40GHz 31 °C
Ivy Bridge 22nm Technology

RAM

16.0 GB Dual-Channel DDR3 @ 665MHz (9-9-9-24)

Motherboard

Gigabyte Technology Co., Ltd. Z77X-UP5 TH-CF (Intel Core i7-3770 CPU @ 3.40GHz) 28 °C

Graphics

VA2448 SERIES (1920x1080@60Hz)
VA2448 SERIES (1920x1080@60Hz)
AMD Radeon HD 7800 Series

Hard Drives

932GB Western Digital WDC WD10EZEX-00RKKA0 (SATA) 27 °C
932GB Hitachi HDS721010DLE630 (SATA) 31 °C

Optical Drives

HL-DT-ST DVDRAM GH24NS90

Audio

Realtek High Definition Audio

Disk drive

Device Kind USB storage
Device Name Disk drive
Vendor SEAGATE
Comment Seagate Backup+ BK USB Device
Location Location 0