Why have some of my photo folders disappeared from the gallery?

[AC Question]

Three folders with a lot of photos have vanished from the gallery app. They are no longer in the albums list.

 

[B. Diddy]

Welcome to Android Central! Which phone? Use a file manager app to look for those directories--are they still there? If so, make sure they don't have a file called ".nomedia" in them, or in a parent directory--that would make the phone ignore the directory when looking for photos to populate the Gallery database.