Used disc 0bytefree ,0 byte used

Hello, i recently encountered this problem, maybe 6mnths ago.I kept searching for help and even posted on Nero forums but no people replied i came across this forum and saw many people having quite the same problem as mine so i would try to seek help from here. This is my encounter below:
This have been going on for almost few months everytime i burnt something into a DVD it was successful but when i insert into my friend’s computer , there is nothing on the disc but 0 bytes free and used space this is weird. Now my friend burnt something for me in DVD again , it happened to me, i cannot see the contents of the DVD but 0 byte used and free space again. I need help on how come this is happening please.
I really hope someone could give me some instructions on how do i see the files , anyway my friend used Nero to burn the DATA, .daa file.
Help would be very much appreciated , this is quite an urgent matter, thanks!