It's almost certainly an encoding issue. There is not only the character set/encoding of the DB, each table and each text field also has a specified encoding (these will show in PhpMyAdmin).
After setting things to Latin1, you may have a mismatch between the DB and the tables or fields. Also, if the data is in one encoding and you change the DB encoding to something else, you have another kind of mismatch.
There's information here that might help, though once things get mixed up beyond a certain point, the solution provided may not work.
http://bobsguides.com/convert-db-utf8.html