lost pictured backup

Hi,a few days ago i backed-up all my photos by doing Backup in airdroid to my gallery files. download was complete but i couldn't open it because i had no winzip on my comnputer. when i tried to open it again (in downloads), i got the message - Unknown network error
and when i try to open the link it says - this webpage is not available...
Is there any way to retrieve these files?
Thank you,
Ori