This is how you can fix your utf8 b0rked drupal database.

The problem:

You are on a shared hosting. Your host upgrades MySQL. Your drupal 4.7 installation is boom broken!

The reason:

Drupal 4.7 sets the database connection to utf8 if you are running MySQL 4.1+
When you upgrade drupal from 4.6 to 4.7 and you are using MySQL 4.1+, drupal will convert the tables to utf8. But it won't if you are running MySQL 4.0.
Your host upgrades MySQL from 4.0 to 4.1+ and drupal will start setting the connection to utf8 BUT MySQL "knows" that the tables are in latin1 encoding. He doesnt know that the data is really utf8 but the tables are latin1. It'll convert the data from latin1 to utf8 and send it to drupal. You'll end up with a broken website due to the double utf8 conversion.

The solution:

Use his script to convert the tables to utf8.

The instructions are near the top.