Readynas Ultra 4 Plus no valid volume exists #25703630

Help! I had a power failure today, and now I am getting a "no valid volume exists" and cannot access any of the shares on the NAS, although they are listed in Finder on my Mac.  However, I cannot access the folders, even though they are listed.  I tried a hard reboot and a soft reboot with no luck.  I need access to my files ASAP for a trial!  Please tell me what I can do to access them again!