hard drive fell over

My Ubuntu 16.04 failed in mid session and failed to reboot with self checking/analysis suggesting hard drive failure (now I’m not so sure this was the case).

I replaced hard drive and then used testdisk with some success to recover files, however I would like to know if given the message below when I connected old drive using external method can I “patch the old hard drive” to simply recover the files The message I get when truing to access is as below… I am not computer literate when it comes to actual Ubuntu syntax and commands… I just like ubuntu system and have managed mainly through try this or try that to get things working your comments and possible assistance would be appreciated

Error mounting system-managed device /dev/sdb2: Command-line    `mount "/mnt/usb-TO_Exter_nal_USB_3.0_201503310007F-0:0-part2"' exited with non-zero exit status 32:    mount: wrong fs type, bad option, bad superblock on /dev/sdb2,    missing codepage or helper program, or other error  In some cases useful info is found in syslog - try dmesg | tail or so.