I agree with the above answer provided by Mancy. In addition to that, if you wanted to add conditional emails to a list or library, you can design a workflow in SPD. If you go to the library and click the Library tab, you can click Workflow Settings, and then Create A Workflow In Sharepoint Designer. This SHOULD redirect you to SharePoint designer, assuming your previous problems don't crop up again.
Here's a link to get you started on workflows, if you haven't made one yet. If your problems opening the library in SPD persist, please attach a screenshot so we can better understand your problem. Thanks!