I built a custom toolbox with multiple geoprocessing tools/models in ArcGIS 10.1. Recently I had to upgrade to ArcGIS 10.3, and now my models are invisible. I can see, move and copy the toolbox in Windows (registering the correct 28mb size), and I can see the actual named toolbox in both ArcMap and ArcCatalog. But I cannot expand the toolbox anywhere to see the models, add it to ArcMap's toolbox framework, or access it in any other way (save as something else etc) in the ArcGIS framework.
HELP!!! I really need to see my models.
Yes I have backups of the file. No I do not have access to ArcGIS 10.1.