It is visible from the question that wordpress (WP) is running out of memory; as the memory allocated by your hosting provider is not sufficient to host your wordpress site, which would eventually result in garbage of your website, increase load time, unresponsiveness (constant loading), missing webpage component and what not.
The perfect solution can only be implemented once the real problem is identified which will appear in error log file (error_log) in home directory where your wordpress (WP) site is currently hosted.
Accessing and Reading Error Log (error_log) File
Accessing and reading error_log files requires hosting access and basic knowledge on how to use hosting panel (cPanel) without creating further chaos
If you are developer or WP pro then open the error_log in the file editor and look for the errors at the bottom of the page as the errors you are looking for are being appending on the bottom, after analyzing errors try to find the fix or type the error in the comment section betow we would try to find a fix for you.
Playing with Installed Theme & Plugins
If you are unable to find the fix yet, then take the following actions:
- Turn off active theme and activate preinstalled theme (Twenty Fifteen)
- Turn off all active plugins
- Browse your site, the error you were facing earlier would have vanished.
- Now activate your theme and most required plugins one by one and check for error.
- Once culprit plugin is identified, don’t installed it again and report it to developer.
Ask your hosting provider to increase your memory limit from 64MB to 256MB.