This is part 2 to the previous How To (how to backup drupal using linux)
If you followed the previous tutorial to create your backups, then this tutorial will allow you to quickly restore Drupal to the previous version.

1. ssh into your server and browse to the directory where your backups reside. This should be your public_html's parent dir. If this isn't the case, you will need to use the -C option to restore to a specific location.
2. extract the public_html backup you made
   

   tar xvfz public_html_bak.tgz

3. restore the mysql backup you made

   gunzip < mysql_bak.sql.gz | mysql -u user -p dbname

Thats it!