"Someone (probably you) has requested a new password for your
account on your Moodle Website'.
Unfortunately your account on this site is disabled and can not be reset,
please contact the site administrator,"
This post addresses a similar issue for 1.8 so it may or may not apply:
I can log in, but keep hitting error messages (mostly: A server error that affects your login session was detected. Please login again or restart your browser.) I'm occasionally getting 'Section errors' but I think that's because Moodle thinks I've logged out before it loads the page, and won't show admin pages to non-admins
However, no one else seems to be able to log in. Tried the suggestion above, but to no avail.
Any ideas to save me trying all the possible settings, one at a time?!
"A server error that affects your login session was detected" probably indicates that your moodledata/sessions folder has incorrect permissions and/or ownership. Permissions should be 0750 and the owner should be something like apache:apache. Can you check please?
For more reading, see also this in the Installation FAQ which has lots of other options to look at.
To elaborate on KW's post, by "something like apache:apache" I think he means the user (and group) Apache runs as. You haven't said whether you have your own server or are using a web hosting service, or what OS you are running under or even whether your webserver s/w is Apache. See http://docs.moodle.org/en/Installation_FAQ#System_information_needed_for_Installation_Forum
Assuming you are using Apache, and your OS is of the *nix variety (Unix, Linux, etc., as opposed to Windows), and your server is all yours (not necessarily yours personally, but your school's, employer's, etc.), then you should be able to determine the username Apache runs as (assuming it is launched by the root user) by looking at the Apache configuration file (usually called httpd.conf) for a line that begins User that is not commented out (i.e. not preceded by a #). That will give you the username. The group name is usually the same, but to be certain you can look for a line, not commented out, that begins Group, which will usually be right after the User line.