If the name is unique (it probably is if it contains a typo), change all occurrences of the name in the database (including table names) and clear the cache.
In D6 the table node_type contains content type machine name definitions. Those names are also used in tables with the prefix content_type_. If the content types aren't used anywhere else, changing the entry and the table name should do it. It's possible that those names have changed in D7.
If the name is unique (it probably is if it contains a typo), change all occurrences of the name in the database (including table names) and clear the cache.
In D6 the table node_type contains content type machine name definitions. Those names are also used in tables with the prefix content_type_. If the content types aren't used anywhere else, changing the entry and the table name should do it. It's possible that those names have changed in D7.