PostgreSQL not working?

Hi, I'm currently having a problem with my PostgreSQL, i'm running a DSpace application working under Solaris OS.
Everything was fine, but I began to receive repeatedly the following error messages to my email:

org.postgresql.util.PSQLException: Connection refused.
Check that the hostname and port are correct and that the postmaster is
accepting TCP/IP connections.

So I've connected to the server and tried to run the postgres console, but I can't get connected by the following error:

psql: could not connect to server: No such file or directory
        Is the server running locally and accepting
        connections on Unix domain socket "/tmp/.s.PGSQL.5432"?

Then I tried to check if the service is running with pg_ctl status command and I've received the following error:

pg_ctl: could not open PID file "/usr/local/pgsql/data/postmaster.pid": Permission denied

And if I try to do the same after sudo root for avoiding the Permission denied problem, then I get that:

pg_ctl: fatal: libreadline.so.5: open failed: No such file or directory
Killed

I just don't know what is throwing me this error and how could I fix it. If any help, I would appreciate it.
Thanks a lot.

Juan.

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