vb.net - WPF Application cannot work all of a sudden -

exception thrown: 'system.windows.markup.xamlparseexception' in presentationframework.dll

additional information: set property
'system.windows.resourcedictionary.deferrablecontent' threw exception.

i error whenever try debug application. haven't touched few days , when left alone, still working, of sudden after yesterday tried , doesn't work. tried on computer, had downloaded application when working , suprisingly doesnt work too. cannot run or crash. please help!