[ubuntu] i did a bad thing can you help me fix it; its really simple im just newbie?

[y4hoo000019]

i read somewhere that it was safe to delete everything in the /usr/src directory, which i did after compiling the 2.6.31-rc8 kernel myself for the first time. alright well now im trying to install wireless STA and when i get to the make part,

root@ryan-laptop:/home/ryan# make -C /lib/modules/2.6.31-rc8-git2-mk/build M=`pwd` clean
make: *** /lib/modules/2.6.31-rc8-git2-mk/build: No such file or directory. Stop.
root@ryan-laptop:/home/ryan#


alright im PRETTY SURE; although im still learning; that this is because this operation calls for the /usr/src/ linux header directory.

so my question is, how do i reinstall the headers for the customized 2.6.31-rc8 build?

can i do a command line operation to extract the information from my system or do i repeat the compiling process all over again (please no).