ftp failed to start

ok I have had Pure-ftp running for 2 or 3 days and yesturday it must have went down. Because when I tyred to access it nothing happened. So i checked the status of it and I got back a message saying ftp unused. I tried to do a restart but it failed. Can any one suggest where I start to to fix this problem. I was thinking about checking the log files but I am not sure where they are located