Missing prefabs and missing prefabs(dummy).

I worked on a school project for Unity called SkullSkew. I worked on it at home and everything turned out fine. I saved the scene and everything in it(models, materials, scripts), but when I arrived to next class, I tried opening my whole project and in the hierarchy tab, it has a bunch of missing prefabs. My assets have all loaded in successfully, but everything in the hierarchy tab says missing prefabs or missing prefabs(dummy). As a noob level unity student, I would appreciate any help you pros can offer.