How did you set the password in the database? The entries in the “password” column are salted hashes of the password, so it’s not totally trivial to just set a password in SQL directly.
As for emails not arriving, that’s really out of Omeka’s hands and depends on your server’s setup for email. Emails could not be sending out from your server at all, could be redirecting to a local user’s mailbox, or could be sending out but getting blocked by the destination servers (mail servers are quite aggressive in their blocking these days). Troubleshooting your email setup is a little out of scope for the Omeka forums though; it’s not really an Omeka-specific issue. If you have some external SMTP server to use, you can configure Omeka to use that instead of your server’s default “sendmail” capability.
Moving beyond mail, if you’re looking at the database anyway though, you can retrieve the password reset token from there and use it without having to actually get the email. Requesting a password reset creates a row in the “users_activations” table, and the value you want out of there is the string in the “url” column. The URL you need to go to would be (under your Omeka installation),
users/activate/u/<the "url" string> (of course just putting the string in there and not including the angle brackets).