500 internal server error

Hello, I have in the past month many problems of “server error” and asked me to be, maybe someone can give me guidance on how to solve them, thanks.

Have you changed anything on your site? What software are you running? 500 errors are sometimes a glitch in the software you’re running. Or an overloaded server. If you have shell access, type the ‘uptime’ command when you’re getting 500 errors. Also, check your logs for what’s happening when the error occurs.

Changed?, I have not changed anything, this is from the October 18.19 in the error log I have failed to identify the problem as there are no records for that period of time, software?, The forum is to phpbb3 and wordpress blog, the command shell I have no access, or at least not access the greetings.