stream line 1156 column0 XMLparse error ：not well formed （invalid token）

hello,i used my SIMULINK to make a model,i saved it !

But when i open the model this morning， simulink showed a error to me.

【stream line 1156 column0 XMLparse error ：not well formed （invalid token）】

no autosave file~_~~_~~_~

please help me,thank you veary much!!!