Hello, I ever had bad experiences with this plugin that caused me not able to login. Here are somethings you may try:
First, and the very first make necessary backup of your important files.
You can use your FTP program or cPanel File Manager to do it. What to backup? Here are the important files:
- .htccess on the root of your website folder
- Entire folder of the plugin wp-content/plugins/better-wp-security
- Entire folder of your website
- The database of the website using cPanel phpMyAdmin
To backup all files in a folder, it will be easier if you compress the entire folder.
Now, things you can try to retrieve your login:
1. Try to delete (or rename) the .htaccess file. If you still unable to login, you should restore it from the backup. But if you can login, it means there are somethings wrong in the file. You need to examine and edit the file (restored from your backup), pay attention of the texts between these lines:
# BEGIN Better WP Security
# END Better WP Security
2. You may also try to use .htaccess file from your other WordPress website that is working correctly. You should not try it if one of the website has WordPress multisite enabled.
3. If you still have no luck, you may try to delete the entire folder of the plugin wp-content/plugins/better-wp-security. You can even combine this option with option no. 1.
If you managed to login to your admin area. You may need to reinstall the plugin (or perhaps uninstall if you not wish to use it). This reinstallation is neccessary to make sure the plugin won't left unused data on your website (database). Once if you're sure your website is working correctly, you should do backup immediately.
These above are based on my experiences, I can't guarantee success. Try it on your own risk. Hope it helps.