Typically when you visit the actual plugins page in admin with the folder renamed it will detect this and deactivate missing plugins by updating the active_plugins option… otherwise it will leave the option intact and unchanged. At least on single site, I am not fully sure on multisite if anything else triggers this update.
However if you have a backup of your database, you should be able to retrieve the active_plugins option and reapply it through say phpMyAdmin. Again this may be different for multisite (though I don’t think it is, just doing it for the correct table should be all you need.)