About the log files you presented:
- dmesg log file tells us that sda1 is needing disk checking with
e2fsck. Please read the paragraph before all the items before doing
anything related to this item.
- Still analising dmesg log file, udevtrigger processes seem to be
failing, but we have to investigate why.
- .xsession-errors log file tells us that a lot of settings can't be
read due to wrong permissions.
So, as a first suggestion: please use e2fsck to try to fix errors in
sdb1 partition. *However*, if df or lsblk say that the mount point of
sda1 is "/", "/home" or anything inside "/home" ("Mounted on" in GNU df,
"MOUNTPOINT" in lsblk), then you *must* do this using a live operating
system. If I remember correctly, after unmounting sda1 (`umount
"/dev/sda1"`), you can do the check by running `e2fsck
"/dev/sda1"`. When done, test things again to see if they are working,
if they are still not working, please report the results (from log files
and command outputs mentioned earlier).
About the external drive: Check if the output of the df and lsblk show
mount points for the "sdb1" part. In GNU df, it should be "Mounted on"
(last column). In lsblk it's the "MOUNTPOINT" (last column too). If such
mount point exists, then you can actually go to that place by doing `cd
"[Mount point, without these brackets]"`. But I suspect that copying
things from sda1 to sdb1 might result in corrupted files.
