Sorry, but you actually screwed it up. You can't undo the chown command. However, since it's just the /var directory that have messed permissions, you could try to fix them manually. On my Ubuntu 12.04 machine, permissions are as follows:

drwxr-xr-x 13 root root     4096 Oct 16 18:48 .

drwxr-xr-x 22 root root     4096 Sep  9 05:02 ..



drwxr-xr-x  2 root root     4096 Oct 17 07:35 backups

drwxr-xr-x 12 root root     4096 Sep  9 09:17 cache

drwxr-xr-x 40 root root     4096 Oct 15 15:44 lib

drwxrwsr-x  2 root staff    4096 Apr 19  2012 local

lrwxrwxrwx  1 root root        9 Oct  8 09:45 lock -> /run/lock

drwxr-xr-x  9 root root     4096 Oct 22 07:35 log

drwxrwsrwt  2 root mail     4096 Oct 21 23:15 mail

drwxr-xr-x  2 root root     4096 Apr 26  2012 opt

lrwxrwxrwx  1 root root        4 Oct  8 09:45 run -> /run

drwxr-xr-x  8 root root     4096 Sep 23 05:31 spool

drwxrwxrwt  2 root root     4096 Sep  9 05:02 tmp

drwx------  2 root bin      4096 Oct  8 09:45 webmin

drwxr-xr-x 25 root root     4096 Oct 16 09:50 www

and /var

drwxr-xr-x 13 root root  4096 Oct 16 18:48 var

Be very careful when you're setting permissions.

"...chown'd everything in /var."

Why would you do that? Did you read that somewhere?