It's important not to confuse the approval of an account, with authorisation of that account to access a site.
A user's account is registered with Voice itself. They can reset their password (which is emailed to them). This is independent of any membership of any sites.
When a user requests membership of a site, the site admins should get a notification of this. Though, if you miss the notification for some reason, you can always find accounts awaiting approval by going in your site admin pages to Users & Permissions -> Members and seeing if there are any members awaiting approval (which will be evident by a "needs approval" link appearing under Member State on the left).
So, if a user is struggling to reset their password, then they should ensure they check their spam folder to see if the new password email has got stuck in there.
If you have lost or changed your email address (and so can't receive the automated email), then drop a note to email@example.com telling us the email address that needs updating, and we can reset your password for you.
Joe - Voice Admin