YES, FEDORA 19.
I saw a lot of information about how to do it but doesn't work with this version. All the tutorials explain the method for older versions of Fedora, i didn't found anything about doing it on the v19 or the v18.
The GRUB menu is different (and i installed the GRUB's version from fedora installation, I only have this system ). I can enter to the recovery console but asks me the root password, so this doesn't solves anything.
If anyone knows a way to do it; or if it's impossible, please tell me why.
Best Answer
For your information, I opened a bug report on the Fedora bugzilla. The solution is:
init=/bin/bash
(editing the kernel line in grub)mount -o remount,rw /
passwd root
touch /.autorelabel
/sbin/reboot -f
The last line (creating the .autorelabel file at the root) force a selinux relabelling of the whole filesystem, which is corrupted since we modified /etc/shadow without any selinux context (because of booting with init=/bin/bash).
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1084400
Updated Fedora wiki with the selinux fix: https://fedoraproject.org/w/index.php?title=How_to_reset_a_root_password#Changing_root_password