Losing my /usr/bin

[akm3]

I have accidentally deleted everything in my /usr/bin folder
As a result of this I cannot even boot my system (except through a bootable cd and via terminal)

Can anybody give me some guidance how to recover from this situation?
I am very concerned about the contents of my '/home' folder, which are still there, but should be kept and backed up even if I need a fresh install

Can I recover, with only accessing terminal? or do I need to reinstall?

If the latter is the case, what is the easiest and safest way to back up my home?

Thanks

PS: I'm using ubuntu 10.10

[TenPlus1]

usr/bin contains many commands that Ubuntu needs to run properly so I'd advise booting from cd and backing up any files you haven't already and re-installing maybe Ubuntu 11.10 if you have it on cd...