I have accidently deleted the system library on my macbook.

Do you have the OS 10.4 discs? Or do you have access to another Mac?

I cannot think of anything simple you can do on the Macbook without an OS disc. The computer has to be booted even for connecting it to another computer. The good news is that your data are still on the drive even though it is not bootable. Do not try anything on the drive before you retrieve the data.

It's not one simple step, but this is one way to get to your data.

1. take the drive out of the Macbook.

2. install the drive in an external enclosure.

3. connect the external to your other mac, and transfer the data.

Once you have done that you can reinstall the OS on the external, and replace the drive in the Macbook.

Example of an enclosure (note, this is just an example):

http://www.tigerdirect.ca/applications/SearchTools/item-details.asp?EdpNo=319523 3&CatId=2781

You can find these at most computer parts stores.

And while you are about it, you should get yourself an OS disk that will work on your computer. You will need it. Check what it is the most recent OS you can use. If it will work on your Macbook, 10.6 is available from Apple. eBay would be your best bet for 10.4.

If you can put the MacBook in Target Disk mode it may not be necessary to physically remove the hard drive from the MacBook. The computer itself will act as the enclosure.

Also, you may be able (if you did not empty the Trash after putting the system library in it) to move the folders back to where they were. Much simpler than having to do a reinstall.

You do need those system disks though.

Since the Mac is not bootable, do you think it will boot in Target Disk mode?

Yes. TD Mode does not depend on software. You can even do it with a brand new empty hard drive - I have.

Thanks. I didn't know that a drive in an unbootable Mac could be a target disk.

Linausan, this is a much easier way to get to your data, than what I proposed. You will need a firewire cable, and two Macs with firewire ports.