Unfortunately your data, profile and bookmarks are on the old computer not the sync. Sync is a sync server between devices not for backups. If you didn't do a backup of your profile, bookmarks, data, logins when you connected back to the sync server it replaced anything that was present there with the new data which had nothing clearing all the previous sync server to one that had nothing to sync to. So at this point unless you can do a backup of the data, profile and transfer them to the new computer sync isn't a backup of the data and when it's gone it's gone as you experienced now.