My external hard drive is telling me that it is unreadable by my mac can i every

I thought that Macs just worked?  

Anyhow, find any other computer.. any, then plug your external drive into that machine. Find another and if both don't read the drive, they you may have to consider opening the device to remove the hard drive. Once removed, you could then try to plug that drive into a desktop pc as, possibly, the drive casing could be at fault and worst case, the hard drive has failed.

Good luck

If the hard drive is formattted as the NTFS file system it may have been encrypted but teh System is was built on.

Actually, I don't think Macs can read NTFS. I do believe they read FAT32 however. Open Applications, go to your folder called "Utilities". Inside, look for disc utility, run that, and see if you can see the drive. If so it probably needs formatted. If not, close that, click the apple at the top left corner of your screen, then click "About This Mac". On the window that comes up, click "More Info". You will see a screen listing different devices and settings. On the left, look for usb(if it connects via usb), then click on that, see if it detects the drive attached to the machine or not.

macs can read NTFS, though you have to do it like linux and use FUSE-NTFS3G

Maybe...but I'm pretty certain they can only format as FAT32, maybe that's why I was not sure.....either way look in those places to see if the mac even sees the drive connected.

OS X can read NTFS formatted volumes but not write to NTFS columes (at least not without a 3rd party solution like NTFS-3G). OS X can both read and write to FAT32.