Dear Robert,
if both JetPack contact form and Contact Form 7 plugins are not working for you, most probably it is a web host issue. Here is a list of recommended web hosting providers for WordPress.
Here is a video tutorial how to downgrade WordPress to an earlier version. You will need to connect via FTP to your web server and manually upload the earlier version of WordPress. Before doing it, you should completely back up your website (all the files on your web server and also the MySQL database).
Best regards
Tomas Toman - TT Themes