I get Error 500 when I click on my Page menu

Try disabling some plugins or remove recently entered functions or hooks in the functions.php.

Did you built your theme by yourself or you downloaded from somewhere, if you have downloaded it then try seeking help on their forum or by contacting them.

If you still facing the problem, then do the following

1. Disable the current theme and activate twenteleven (or any default theme you have) and see if the problem still exist. (if the problem exist do the step 3)

2. Disable all the plugins and check.

3. Re-upload wp-admin if nothing seems working.

Let me know if any of the above is working.

Thanks man, I really appreciate your reply. It seems the problem was a plugin and so I deactivated it and that fixed it. I was a little thrown my how to reconnect databases part of the error message as I have not got a lot of knowledge regarding MySql and PHP. So thanks again

Whenever you get an error dont be Panic…just rename the Plugins that you recently installed to 1 and check it. Trial and error always help me good in troubleshooting