inquiry

Hello evryone.
After a recent photo shoot, I cam across this situation.
The person can not open a file with either extension .psd nor .nef.
They were downloaded from my camera, opened and processed in photoshop.
I left the original in tact, processed/saved the psd.
Blck and whites and sepia images were created and put into another folder.
Probelm: 
How can this person open the photoshop (.psd) or nef document?
If so with what application?
If not, what can be done?

Thank you for your time.

Louis