It is law in most places that sentimental and non-valueable personal items be returned to the storage unit management.

Things like bills, mail, photos, legally, all must returned, and you can collect them.

This doesn't help with the valuable art or furniture, but at least you should be able to recoup your sentimental stuff like the photos.

PLEASE reach out to the storage and let them know there are those things in the unit. They can relay that info to the buyer, and they can set your stuff aside for you to collect.