How to Fix a WordPress Backend

Repair Compatibility Issues
1. Sign in to your WordPress site, and click 'Plugins.'
2. Click the 'Active' tab to display the list of active plugins. Click the bulk select box to highlight all the plugins on the page.

3. Click the bulk arrow tool. Choose 'Deactivate.' This deactivates all the plugins.
4. Check your WordPress admin panel and see if the problem is fixed. If it is, there was a compatibility problem with one or more of your WordPress plugins.
5. Click the 'Inactive' tab to display the plugins you deactivated. Click 'Enable' beneath each plugin, one by one. After enabling each plugin, check your WordPress plugin. This step-by-step approach allows you to find the plugin that caused the problem. If the admin panel problems returns after enabling a specific plugin, you've found the culprit. Deactivate the plugin again, and click 'Delete' to remove it.
Reinstallation of the WordPress Admin Panel
6. Visit WordPress.org, and download the latest WordPress software package. Open the ZIP file and extract the contents to your desktop, or to a personal folder.
7. Open the main WordPress folder. Inside, you'll see a folder marked 'WP-Admin.' This is the folder you'll replace on your server to reset the WordPress admin panel.
8. Access your server using the host's file program, or an FTP program. If you don't know how, contact your host for specific instructions. You'll need the IP address and FTP username and password.
9. Copy the 'WP-Admin' folder onto your server. You should be asked if you want to overwrite the current 'WP-Admin' folder. Select 'Yes.' Check your WordPress admin panel. The problem should be fixed.