check you pages settings, the ones that add and edit and also the one that shows the data, also check what collision your tables in the database are set.
Why this for special characters example Spanish you need to use on the beginning of the page these lines of codes
<html xmlns="http://www.w3.org/1999/xhtml" xmlns:wdg="http://ns.adobe.com/addt">
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
the colored line is the most important for special characters i use that one or the charset = UTF-8
Also check your database it should tell you what type of characters its using.
Example if your database settings are latin1_general_ci or latin1_german_ci or latin1_spanish_ci or any other latin settings you need to use on the top of your page charset=iso-8859-1, if its utf then u have to use utf-8 and so on depending on your lengauje.
Hope this helps :)