Cannot boot even in recovery mode - how to reinstall without formatting?

[Amurko]

I accidentally deleted some critical system files on one of my ubuntu systems to the point where it won't even give me a login prompt in Recovery mode. It's running 9.04 and I have a working 9.04 live cd.

Is there any way to reinstall the base system without having to back everything up and reformat?

Note I don't have a separate /home partition but I don't want to go through the trouble of backing everything up and reformatting unless it's absolutely necessary.

I read some threads here and it says to try doing:

apt-get install ubuntu-desktop

Unfortunately, I cannot boot up this system without using a live CD.

[zvacet]

You can make separate home following this (http://psychocats.s465.sureserver.com/ubuntu/separatehome) or this (http://www.ivankuznetsov.com/2008/04/moving-home-to-its-own-partition.html) guide.After you do that reinstall Ubuntu on top of root partition and don´t format home.

[bjm442]

I have the same problem. I was going for 8.10 to 9.04, and nothing comes up. I also don't want to reformat, since my e-mail is on that pc. not sure what to do next.

[mosaic2s]

To save your e-mail data, check out profile folder.
Try USB pen drive for booting the system and transferring e-mail data on that.