arcgis pro model builder icon changed can't open how to recover

[steven]

arcgis pro model builder icon changed to like a page icon and can't edit anymore

What cause this?

how to recover the model builder 

[Laura]

an you access it going through the geoprocessing pane instead? 

[steven]

Laura thank you for your reply . still can't change anything edit button is not work. is there a way to change this back to model builder?