dump from /var/lib/postgresql to recovery

Hi,
i've a database that work perfectly until yesterday, that when i try to
access into database from every commands like:
"psql -U postgres db_name"
Postgresql gives me an error:
"server closed the connection unexpectedly
This probably means the server terminated abnormally
before or while processing the request.
"
This happens only when i try to access into this database, because when
i try to access into "template1" database it works perfectly, without
errors.

My question is this: There is a method to recovery, dump, check... or
other, my database from "/var/lib/postgresql" cluster directory, without
using service/daemon applications?

Thank you.

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