Please help -- Postgres stopped responding ....

Hello Team,

I am new to Postgresql. Postgresql suddenly stoped responding. Below is what I checked.

[root@server]$/etc/init.d/postgres status
dead but pid file exists

[root@server]$ uptime
 20:33:26 up 63 days, 22:57,  4 users,  load average: 1.73, 2.26, 2.43

My questions are,

1. Which postgresql database logfile needs to checked for information on why postgres stoped responding?

2. What else besides logfile can be checked ?

Thanks,

Savio