Firefox doesn't store your email, it would be stored (if still available) by your mail client (e.g., Thunderbird) or your mail site (e.g., Yahoo, Gmail, Hotmail). If someone here shares a webmail service with you, they might be able to help. Otherwise, try the support for your mail service.

On another topic...

The forum software detected your Firefox as version 15. Is that correct?

Version 15 is not secure; Mozilla discloses security flaws after each new release. Is something holding you back from upgrading to Firefox 22? Please let us know so we can suggest solutions or workarounds.

If Help > About Firefox shows Firefox 22.0, you may need to clear the preference that is misreporting your version number. See: How to reset the default user agent on Firefox.

Note that on Linux you may need to check if you meet the System Requirements for the current release.

• http://www.mozilla.org/en-US/firefox/22.0/system-requirements/

If you can't update via the software repositories of your Linux distribution then you can consider to download and install the version from the Mozilla website.

• http://www.mozilla.org/en-US/firefox/all.html