No, you were not meant to delete that, and it's not the end of the system. It's not like of my High School buddies doing "deltree /y C:\"... did you delete /usr/src or just clobber everthing in /usr/src? Just fetch a new vanilla (stock) kernel from kernel.org
or apt-get/aptitude install the most current one (be sure to check that it's the srcs and not a prebilt binary kernel)
> A: Yes.
> >Q: Are you sure?
> >>A: Because it reverses the logical flow of conversation.
> >>>Q: Why is top posting frowned upon?