Hi,
Please follow given below steps-:
1- Deactivating all plugins to see if this resolves the problem. If this works, re-activate the plugins one by one until you find the problematic plugin(s).
2- Switching to the Twenty Eleven theme to rule out any theme-specific problems.
3- Resetting the plugins folder by FTP. Sometimes, an apparently inactive plugin can still cause problems.
4- Re-uploading the wp-admin and wp-includes folders from a fresh download of WordPress.
Thanks 🙂
With Best Regards
Mohammad