Ubuntu block out of mac

[don't do it]

I know this is the windows fourm but i need some serious help.
I tried to install Ubuntu 9.04 on 500 GB external drive and it will now no longer boot Ubuntu nor Mac. I need to know how to fix this.

Things already tried:
*Backing up harddrive and installing Snow Leopard (10.5.4 is what it is)
*Deleting the external harddrive and reformatting it.

I want to be able to keep all my mac files.
The file with a ? appears when the Ubuntu livecd is not in. (that is the only thing that boots)

If you need more information please let me know

 

[illinois2011]

Does your computer boot without the external plugged in?

 

[don't do it]

your saying that all my files are going to have to be deleted

 

[illinois2011]

Not necessarily. Ubuntu just has a funny way of messing up the boot process. I had a dual boot setup once on my pc with Windows and Ubuntu and got to where I couldn't boot at all. If you have an OS X boot partition on an external drive, it may be fairly easy to go in and recover your files before you have to wipe the drive.