If you received a "white screen of death", it might be worth trying to delete the Jetpack plugin files, and then reinstall the plugin manually, as explained here:
http://codex.wordpress.org/Managing_Plugins#Manual_Plugin_Installation
If that doesn't help, I would need to know more about the issue in order to be able to help. Could you for example post your site URL here, so I can have a look?
If you want it to remain private, you can also contact us via this contact form:
http://jetpack.me/contact-support/