Comment 21 for bug 150259

2.6.22-12 is probably available on the Gutsy Beta CD (you could add this as a temporary APT resource). Otherwise I don't know, I didn't realise it had been removed from the repos.

You are searching for this right, aren't you? 2.6.22-12 (note the hyphen, not full stop, between the last two numbers).

If you type at the command prompt,

sudo apt-get install linux-image

and hit the TAB key to see the options available, what do you see? I get the following list:

linux-image linux-image-debug-2.6.22-14-generic
linux-image-2.6 linux-image-debug-2.6.22-14-server
linux-image-2.6.22-12-generic linux-image-debug-2.6.22-14-ume
linux-image-2.6.22-13-generic linux-image-debug-2.6.22-14-virtual
linux-image-2.6.22-14-386 linux-image-debug-386
linux-image-2.6.22-14-generic linux-image-debug-generic
linux-image-2.6.22-14-rt linux-image-debug-server
linux-image-2.6.22-14-server linux-image-debug-ume
linux-image-2.6.22-14-ume linux-image-generic
linux-image-2.6.22-14-virtual linux-image-rt
linux-image-2.6.22-14-xen linux-image-server
linux-image-2.6-386 linux-image-ume
linux-image-386 linux-image-virtual
linux-image-debug-2.6.22-14-386 linux-image-xen

... but of course I already had 2.6.22-12 installed, which may be why I see it.