In terminal try this command:
ps -ef | grep postgres
you will see like:
501 1445 3645 0 12:05AM 0:00.03 postgres: sasha dbname [local] idle
The third number (3645) is PID.
You can delete this
sudo kill -9 3645
And after that start your PostgreSQL connection.
Start manually:
pg_ctl -D /usr/local/var/postgres start