Master server stoped working

Hi
All of sudden my master server goes down pls see the error below when tried
to start it

Sep 20 14:33:30 Master postgresql(at)9(dot)5-main[2162]: Error: could not exec
/usr/lib/postgresql/9.5/bin/pg_ctl /usr/lib/postgresql/9.5/bin/pg_ctl start
-D /var/lib/postgresql/9.5/main -l
/var/log/postgresql/postgresql-9.5-main.log -s -o -c
config_file="/etc/postgresql/9.5/main/postgresql.conf" :
Sep 20 14:33:30 Master systemd[1]: postgresql(at)9(dot)5-main(dot)service: Control
process exited, code=exited status=1
Sep 20 14:33:30 Master systemd[1]: Failed to start PostgreSQL Cluster
9.5-main.
Sep 20 14:33:30 Master systemd[1]: postgresql(at)9(dot)5-main(dot)service: Unit
entered failed state.
Sep 20 14:33:30 Master systemd[1]: postgresql(at)9(dot)5-main(dot)service: Failed with
result 'exit-code'.

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Arvind rao chikne
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