I've Done A Really Bad Thing

[John Graddy]

I'm afraid that I've done an incredibly stupid thing.  First. I removed 
IPV6 from my system.  Second, I upgraded to Ubuntu13.04. Third, I 
misplaced the instructions for deleting IPV6.  Now, I evidently need 
IPV6 and don't know how to reverse my past sins  can someone help me 
out?   I think that I removed ipV6 by changing a configuration file and 
then remaking Grub.

Thanks for any advice. I can't even find the configuration file in 13.04
Thanks in advance for any advice.

John