Postgresql 9.3 Server will not start after Ubuntu Upgrade

I recently upgraded my OS from Ubuntu 14.04 LTS to 16.04 LTS and since,
postgresql refuses to re-start. I am concerned that if I poke around too
much, I may lose my old data. I have consulted various web postings here
and in ubuntu forums, and have not found an obvious solution. But please
excuse me, I am not a Linux expert, and I had a friend help me with
setup issues several years ago. They are no longer available, and I am
having trouble getting things to run.

Again, this is after upgrading from ubuntu 14.04 LTS to 16.04 LTS.
Consulting the book "PostgreSQL: Up and Running", I have looked at my
.conf files in /etc/postgresql/9.3/main, things seem to be in order.

Here are the un-commented lines of postgresql.conf: (I have NOT changed
these, they are the settings that used to work in ubuntu 14.04)

NOTE: my comments have // at beginning of the line, these lines are NOT
in the .conf file

data_directory = '/var/lib/postgresql/9.3/main'        # use data in
another directory
hba_file = '/etc/postgresql/9.3/main/pg_hba.conf'    # host-based
authentication file
ident_file = '/etc/postgresql/9.3/main/pg_ident.conf'    # ident
configuration file

external_pid_file = '/var/run/postgresql/9.3-main.pid'            #
write an extra PID file

listen_addresses = 'localhost'        # what IP address(es) to listen on;
port = 5432                # (change requires restart)
max_connections = 100            # (change requires restart)
unix_socket_directories = '/var/run/postgresql'    # comma-separated
list of directories
ssl = false                # (change requires restart)
ssl_cert_file = '/etc/ssl/certs/ssl-cert-snakeoil.pem'        # (change
requires restart)
ssl_key_file = '/etc/ssl/private/ssl-cert-snakeoil.key'        # (change
requires restart)

// In the logging section, these are the only entries (is this why I
cant see any log files when I try to start the server??)
log_line_prefix = '%t '            # special values:
log_timezone = 'Navajo'

// In Client Connections section, these are the only items active:
datestyle = 'iso, mdy'
timezone = 'Navajo'
lc_messages = 'en_US.UTF-8'            # locale for system error message
                    # strings
lc_monetary = 'en_US.UTF-8'            # locale for monetary formatting
lc_numeric = 'en_US.UTF-8'            # locale for number formatting
lc_time = 'en_US.UTF-8'                # locale for time formatting
default_text_search_config = 'pg_catalog.english'

The pg_ctl.conf file is basically empty

The pg_hba.conf file has these active lines:
local   all             postgres                                trust
local   all             all                                     peer
host    all             all             127.0.0.1/32            trust
host    all             all             ::1/128                 md5

The start.conf file has one active line, 'auto'

The pg_ident.conf file has no entries.

When I try to start postgresql service using this line:
service postgresql reload

then check running services using this:
systemctl list-units --type service --all
I see the lines related to postgres as follows:
postgresql.service                 loaded    active   exited  PostgreSQL
RDBMS
● postgresql(at)9(dot)3-main(dot)service        loaded    failed   failed 
PostgreSQL Cluster 9.3-main

And, looking for log files, I find none.

If I try to start pgAdmin, I see two servers on localhost, when I tried
to connect, I get an error first that says it can not open the log file,
on clicking that I get an error can't open file /home/XXX/.pgpass,
permission denied. Then I get a prompt for the password for postgres,
and when I enter the known password for the user, I then get a big 'Guru
Error' box with a message:
could not connect to server: Connection refused Is the server running on
host "127.0.0.1" and accepting TCP/IP connections on port 5432?
Note that the postgresql.conf file does list 5432 as the port number.

I hope someone has the patience to look this over and suggest remedies. --

Ken Beck
Liberty, Utah, USA