I have added a few controls on a form with "Default View" set to "Continuous Forms". Prior to my additions, I could enter information into, and edit information already in, the control. Now I can neither enter nor edit.

Most likely when you added the new controls you created a recordset that cannot be updated. Review the rules in Access help for Updatable recordsets. I believe typing Updatable into the help will get you there.

Did you add the controls by adding fields from another table? That could create an uneditable recordset.