Data recovery - damaged filesystem - Ask Ubuntu

i've installed new distribution (ubuntu 16.04, before ubuntu 14.04). before installation i've copied data on external hdd. when trying copy back, not able access it. seems file system (ext4) damaged. able see fdisk -l commnad not mount it. i've created mounting point in /media named external

i've run sudo mount /dev/sdb1 /media/external

the output is:

 mount: wrong fs type, bad option, bad superblock on /dev/sdb1,         missing codepage or helper program, or other error        in cases useful info found in syslog - try       dmesg | tail or so. 

i've tried mount -t ext4 /dev/sdb1 /media/external

output:

mount: special device /dev/sdb1 not exist maria@maria-vostro-3360:/media$  

i trying boot computer on live ubuntu 14.04, system installed when copying data on external disc, didn't help.

gparted shows unknown file system , under details there following:

i've run testdisk. i'm not sure if i've done correctly (for exemple don't know if should choose no partitionned or there 1 partition on disc. i've choose default options, i.e. partitioned, type - linux. result of deep search was"

disk /dev/sdb - 320 gb / 298 gib - chs 38913 255 63      partition               start        end    size in sectors  d linux                    0  32 33 38913  70  5  625139712  d linux                 1215 170 44 38913  70  5  605612032  d linux                 1490 100 19 38913  70  5  601198592  d linux                19611 118 28 25015 239 56   86822912 

since seems filesystem damaged wanted run fsck. i've run sudo fsck -r /dev/sdb1 , got this:

fsck util-linux 2.27.1 e2fsck 1.42.13 (17-may-2015) ext2fs_open2: bad magic number in super-block fsck.ext2: superblock invalid, trying backup blocks... superblock has invalid journal (inode 8). clear<y>?  

since don't understand doing, typed no, don't want mess more , loose data defenitly. output was:

fsck.ext2: illegal inode number while checking ext3 journal /dev/sdb1  /dev/sdb1: ***** file system modified *****  /dev/sdb1: ********** warning: filesystem still has errors **********  /dev/sdb1: status 12, rss 3040, real 816.797699, user 0.004000, sys 0.000000 

update: in testdisk i've tried check non partitioned media. advanced - filesystem utiles shows primary partition unknown filesystem. i've tried change ext4 , entered list. output was: can't open filesystem. filesystem seems damaged.

update 2: following @heynnema's advice i've managed recover still don't know what. files , directories in 1 directory lost+found wired names (starting # , after different numbers). of files has name of file had in computer name doesn't match content. open folder lost+found have use sudo , i'm not able copy it:

root@maria-vostro-3360:/media/maria/9db3c007-4387-4ea8-a61c-b12fa10049bc/lost+found/#3670019# cp -i /media/maria/9db3c007-4387-4ea8-a61c-b12fa10049bc/lost+found/#4718697/ /home/maria/desktop/odzysk/1 cp: omitting directory '/media/maria/9db3c007-4387-4ea8-a61c-b12fa10049bc/lost+found/#4718697/' 

the .odt file after opening looks this: loading long , got message contains invalid characters. while trying change encoding, file closed due error.

after extended conversation in comments , in chat... , close question... here's did...

1. performed fsck on external hard disk drive
2. all recovered files ended in lost+found folder
3. we changed name , ownership of folder , files
4. copied folder external hard disk drive desktop
5. reviewed few of files , found missing data