Ouput Buffering Error

Disable your plugins. If the problem goes away start re-enabling them on by one until you find the problematic one.

On disabling each plugin manually this error changes for every plugin and at the end after disabling all plugins now its giving error,

Fatal error: Allowed memory size of 33554432 bytes exhausted (tried to allocate 51599 bytes) in /home/ddlwebsi/public_html/girlzcorner.com/wp-includes/functions.php on line 316

Try:
– switching to the Twenty Eleven theme by renaming your current theme’s folder inside wp-content/themes and adding “-old” to the end of the folder name using FTP or whatever file management application your host provides.

– resetting the plugins folder by FTP or phpMyAdmin.

I have resseted my plugins folder but still there’s a same error ??

Resseting Plugins has fixed this error at some options but now this fatal error is only showing when i set featured image manually to the post.

Fatal error: Unknown: Cannot use output buffering in output buffering display handlers in Unknown on line 0

1. Something (plugin or theme) is turning on output buffering (https://php.net/manual/en/function.ob-start.php).
2. Most likely you are getting an error (possibly Out Of Memory), which can’t report exactly what it’s error is because buffering is on.

You need to fix problem 2. To debug what that is, turn off problem 1 (buffering). To do that, follow the original advice of disabling plugins/theme until the vague error becomes a specific error.

If the specific error is “Fatal error: Allowed memory size of 33554432 bytes exhausted” then talk to your host about memory availability.

Are you using SABRE plugin or any security plugins that interferes with login of your blog. If yes, then you might not have configured it properly. Or it may have been causing some trouble with your server. Try disabling such plugins and deleting any records or tables associated with it.
Make sure you backup everything before clicking delete button anywhere.

Also, are you getting it on your dashboard or everywhere on your blog interface? When I had the same problem it was just on the dashboard, try going to yoursite.com/wp-admin/plugins.php

Its a golden rule (mine :D), whenever you see

Fatal error: Allowed memory size of ___________ bytes exhausted (tried to allocate _______ bytes) in some_file_path.php on line some_line_number. Always first check your php memory allocation size, most of the hosting providers have set it lower ( then wordpress needed / minimal requirement), specially on shared hosting. So if you can increase the memory size first try that and it will save you hours and sometimes days of headache.

Hope that helps at-least a couple of WordPress users if not all.