Deactivation "Better WordPress Security" > Server Error

In the installed plugins section of the dashboard I accidentally deactivated the “Better WordPress Security” plugin, the name might not be exact but the popular version. As the plugin controls the .htaccess etc the deactivation has caused a server error. I cannot reach the dashboard, nor can I visit any pages.

I can however access the ftp folder, perhaps I just need to change some permissions? Thanks in advance for any help on this.