This is a question on Photon, not for the IDE. Since we don't have a Photon project on the community, I will forward 
your question to our Photon team.

> I am experiencing a problem with the photon interface. Indeed when the file 
> manager is opened, it does not show anymore the files which is very 
> inconvenient to
> manage files.I guess it is a trick with the configuration but did not manage 
> to see where. 


Does it help if You do the following:

close Your filemanager

in a terminal do:

cd $HOME/.ph
rm -Rf pfm

pfm

Something better ?

Hope this helps.
Jeevan