Re: I really messed up my computer
Since you can boot with the LiveCD and it shows your hard drive, try using gparted to format it (with sudo). If that does not work, though I cannot really pinpoint what the issue is, if you can get into your laptop bios with your hard drive connected, you might be able to do a low level format if you have that option - this restores the hard drive to its factory settings. All your data however, will be lost beyond any form of recovery (not even by tools that can still recover some stuff after a normal format). The fact that the Live CD does show partitions and not nothing at all means (bless yourself at this time) that the hard drive is not short circuited (which could have been the case since your desktop does not boot when this HD is connected - happened to me once a long time ago and I lost a huge amount of data then; nothing irreplaceable though ).
Be formless, shapeless... like water. Now you put water into a cup, it becomes the cup; you put water into a bottle it becomes the bottle; if you put it in a teapot it becomes the teapot... Now water can flow, or it can crash... Be water my friend