If your plugin is deactivated (and you did not do it), there are two possibilities.
A plugin was deactivated due to an error
There was an error in which case you will see an error ID at the top of WordPress dashboard when you log in.
Contact support and add the ID of the error to the ticket.
Plugins are taking too much memory
When plugins are updated, they require much more memory then when in use and that’s when the issue can occur. If you have more than 15 plugins, we highly recommend you deactivate plugins that are not in use.
If the issue still occurs, contact support and list the plugin(s) that were deactivated.