Getting data with python

I'm trying to write a python program, in which python searches for files on an external harddrive. I can get python to tell me whether the files exist, but not to retrieve them. I'm rookie with python so I hope somebody can help me.

The files the program has to retrieve are raster datasets and are used in a model builder program then. The complete modelbuilder program works, the python part does not.

I hope somebody will be able to help me

Dorien Janssen