i succesfuly mounted my hdd to openwrt with mount/dev/sda1 /folder name
beacuse of the transfer was slow i removed the hdd from my nas and mount it to my pc directly
i copy my files to it and then again mounted on my nas with mount /dev/sda1 /folder name
my problem is that the openwrt seems it cant find my files
i can only see the files i copy throw ethernet to it
Were all the files visible when you mounted originally? If so you might try rebooting your router, make sure to keep your drive connected while rebooting (and then remounting if necessary).
What filesystem (ie what format) is the HDD? NTFS? Ext4? etc.
Post the output of
mount from a ssh connection to your openwrt device.