500 Internal Server Error?

I was configuring with my Prestashop theme, then all the sudden the following shows up and after then, none of my pages works, the following keeps showing up. Can somebody help?

Internal Server Error

The server encountered an internal error due to .htaccess misconfiguration.
Please check your .htaccess file within this or upper directories for syntax errors.

Diese Anfrage konnte auf Grund eines .htaccess Konfigurationsfehlers nicht bearbeitet werden.
Die Überprüfung auf Syntaxfehler in der .htaccess-Datei in diesem oder einem übergeordneten Ordner ist erforderlich.
Apache/2.4 Server at beautybeat.bplaced.net Port 80


I took a look at your .htaccess file, Options +FollowSymLinks must not be set in this case. However, the error is gone but the resulting page is blank.