Plugin Error -what can I do?

My site has been fine until 2 days, started giving out 500 internal server error messages when I published new post. So I looked on this forum and added 2 lines of text to .htaccess and still the same, so changed them back.

Then I looked in my cpanel error log, and found a fatal error with the xml sitemap, however when I click on plugins installed, I get the following message.

$time) { if ( isset($recent[ $plugin ]) ) unset($recent[ $plugin ]); } if( $recent != get_option(‘recently_activated’) ) //If array changed, update it. update_option(‘recently_activated’, $recent); wp_redirect(‘plugins.php?activate-multi=true’); exit; break; case ‘error_scrape’: check_admin_referer(‘plugin-activation-error_’ . $plugin); $valid = validate_plugin($plugin); if ( is_wp_error($valid) ) wp_die($valid); error_reporting( E_ALL ^ E_NOTICE ); @ini_set(‘display_errors’, true); //Ensure that Fatal errors are displayed. include(WP_PLUGIN_DIR . ‘/’ . $plugin); do_action(‘activate_’ . $plugin); exit; break; case ‘deactivate’: check_admin_referer(‘deactivate-plugin_’ . $plugin); deactivate_plugins($plugin); update_option(‘recently_activated’, array($plugin => time()) + (array)get_option(‘recently_activated’)); wp_redirect(‘plugins.php?deactivate=true’); exit; break; case ‘deactivate-selected’: check_admin_referer(‘bulk-manage-plugins’); deactivate_plugins($_POST[‘checked’]); $deactivated = array(); foreach ( (array)$_POST[‘checked’] as $plugin ) $deactivated[ $plugin ] = time(); update_option(‘recently_activated’, $deactivated + (array)get_option(‘recently_activated’)); wp_redirect(‘plugins.php?deactivate-multi=true’); exit; break; case ‘delete-selected’: if ( ! current_user_can(‘delete_plugins’) ) wp_die(__(‘You do not have sufficient permissions to delete plugins for this blog.’)); check_admin_referer(‘bulk-manage-plugins’); $plugins = $_REQUEST[‘checked’]; //$_POST = from the plugin form; $_GET = from the FTP details screen. include(ABSPATH . ‘wp-admin/update.php’); $title = __(‘Delete Plugin’); $parent_file = ‘plugins.php’; if ( ! isset($_REQUEST[‘verify-delete’]) ) { wp_enqueue_script(‘jquery’); require_once(‘admin-header.php’); ?>

‘, sprintf(__(‘%s by %s’), $plugin[‘Name’], $plugin[‘Author’]), ”; ?>

When I click on delete plugins, I am redirected to my blog page 404 – page not found!

What can I do to reolve this, as the blog is working fine but I cannot add fresh material.

Any help is appreciated.