Cannot edit prefix, suffix, first name or last name of new or existing Individual
SOLVED.
The update to 6.4.4 seemes to have deleted some values in the 'civicrm_option_value' table. These options reffered to the option group with the name 'contact_edit_options' in the table 'civicrm_option_group'. The options for 'First Name', 'Last Name' etc. were no longer present and if these aren't present those fields just dissapear from the contact while editing. They also do not longer show on the 'display preferences page'.

It seems the upgrade to CiviCRM 4.6.4 I did didn't take well and deleted those option values, or it could be that the upgrade needed to add these option values in order to make 6.4.6 work but didn't succeed in adding these to the database, I am not sure. I did experience problems with my database before doing the 4.6.4 upgrade and didn't get the message that the upgrade was succesfull, so it is difficult for me to say what actually caused the problem.

The easiest way to check for the possibility of the existence of this kind of problem is to install a seperate new empty installation of the same CiviCRM version and compare these two tables for options that are present in the 'empty' CiviCRM but not in the CiviCRM with the problem. I was ble to get the name of the option group that had the problem by checking the code from the 'display preferences page'.

Hope this helps someone with the same problem. I spend days figuring this on out.