Help with powerbook, not reading external hard drives

i know that people have mentioned something similar here before, but I didn't see a thread that helped my situation, so I'm adding a new one.

I have a Powerbook G4

I have a WD tera hd

they used to get a long fine and talk to each other just fine. Now, it won't work.

I can't read any external hard drive on my laptop, but both mine and my friends smaller 250g WD HD were visible on his mac.

I don't understand why they won't show on my computer. they don't show up on the disk utility either.

I hope some one can help.

Thanks!

yes, i'm transferring data with a usb 4g stick now. It's not the usb plug.