[URGENT] How Do I Fix Thunderbird Email Client User Profile Corruption?

[Teo En Ming]

Dear Ubuntu users,

I am using Lubuntu 15.10 Linux as a virtual machine in a Windows 10
host operating system. The hypervisor/virtual machine manager I am
using is Oracle VM VirtualBox 5.0.4 for Windows hosts.

Currently, I have 2 user profiles in my Thunderbird email client which
is running in Lubuntu 15.10 Linux.

I could start Thunderbird using the first user profile without any problems.

Recently, I started encountering problems with my second Thunderbird
user profile. Previously, I could start my second Thunderbird user
profile without any problems. But now, whenever I start Thunderbird
using the 2nd user profile, the folder pane on the left would not show
up at all.

I have tried the following 2 suggested fixes.

(1) As suggested by the Mozilla Thunderbird knowledgebase, I have
tried removing the files folderTree.json and session.json and
restarting Thunderbird. However, the folder pane on the left would not
show up at all and it is still missing.

(2) The Thunderbird email client version in Lubuntu 15.10 Linux is
31.8.0. I have downloaded the latest Thunderbird email client version
38.3.0 from the official Mozilla Thunderbird website. Then I performed
the upgrade to Thunderbird version 38.3.0 as follows:

$ cd /usr/lib

$ sudo mv thunderbird thunderbird.31.8.0

$ cd

$ cd Downloads/

$ tar xfvj thunderbird-38.3.0.tar.bz2

$ sudo mv thunderbird /usr/lib

$ cd /usr/lib/thunderbird

$ ./thunderbird

But still, the folder pane on the left would not show up at all and it
is still missing.

Hence, I suspected that my second Thunderbird user profile is
corrupted. How do I fix a corrupted Thunderbird user profile? It's
either I fix Thunderbird or Thunderbird fix me.

I have considered running the Linux command "fsck /" but fear damaging
the root filesystem which is already mounted in a running Linux
operating system.

I am looking forward to any suggested fixes.

Thank you very much.

Yours sincerely,

Subtle Denial of Medical Treatment by the Singapore Government for Mr.
Teo En Ming (Zhang Enming)
https://www.scribd.com/doc/258700156/Subtle-Denial-of-Medical-Treatment-by-the-Singapore-Government-for-Mr-Teo-En-Ming-Zhang-Enming
7th Oct 2015 Wednesday 6:37 PM Singapore Time