You can download the application again from the Sony's support page. Access the website, then click the available tabs to see the models supported, as well as information about the product and how it needs to be used.
HD-EG5B / HD-EG5S
HD-PG5 / HD-PG5B / HD-PG5U / HD-PG5W
Unfortunately, I can't say if you will have the possibility to recover your files if the software was deleted by accident.