Recently I downgraded from Yosemite to Mavericks in a vain attempt to solve a wifi connectivity problem. I was then informed that to retrieve data the that I had stored on an external hard drive and migrated to the Mavericks system, I needed to return to Yosemite, which I duly did. The data migration was accomplished satisfactorily on each occasion. However I find that the photos (iPhotos) and music (iTunes) I had stored on the original system are no longer immediately accessible. I'm sure that they were fully transferred to the external hard drive (a WD My Passport with 1 ter of storage space) and therefore must exist somewhere in the restored Yosemite system. Can anyone tell me how to restore them to the Photos and iTunes applications? Thanks.