Attempted urgent restore, Norton can't find backup set

I have been storing backup files on an external hard drive. The last backup failed as there was not enough space on that drive but it didn't overwrite the existing backup it is still there. I moved some files and made space, renewed my subscription to Norton and did some clean up on old folders. I inadvertantly deleted some that I wanted to keep. Attempted a restore and Norton cannot find any backup sets to restore from. (I can see them on the ext. drive.)

 

Have been online with techs twice. They removed and reinstalled Norton, had me run a test backup to make sure Norton could find the new backup set (it could). They had me run a portable restore. All to no avail. I am desperate to recover my old files. Can anyone help???