Determine geographic coordinates

There is allready a website using Google Map Api, but some of the geographical data stored in the php-database are not correct. The reason could be some special characters in the german addresses. So please update the existing database. When I add new addresses to our database lat and ing are not automatically added to the data. That should be changed! Sometimes I add a bulk of addresses by using a csv-file and phpmyadmin - of course without the geographical data. I need link in our website to add these geographical data to all files which doesn't contain the data until now. That'ts all !