static method

I am working with winforms and in the file section I have a file that needs to be accessed from a static method.  I get the following error message on fields that are associated with that file...error code COBCH0969, Cannot access object data from a static method or field.    In order to fix these compile errors I put the keyword static on the FD of the file.  When I run the program in this way I get a runtime error of NullRefernceException -- object reference not set to an instance of an object. 

Now I realize that I could make the method as public and my problems would go away, but I really don't want to have to do this.  How can I resolve this issue?  Thanks