I have a Macbook and used audacity in the past to save voicemails from my phone to my computer and it worked perfectly. However, when I open the files now I get a message saying “Couldn’t find the project data folder:” and when I hit OK I get “Could not load file:” - these files are saved as .aup - how can I retrieve these audios that I once was able to listen to? Thanks so much!
An Audacity project consists of two parts: the _data folder that contains the actual audio data and the .aup file that specifies how those audio bits go together. They must remain together in the same folder.
If appears you have moved or misplaced either the .aup file or the _data folder. See if you can find the _data folders that have the same names as the .aup files.
See Managing Audacity Projects in the manual.
– Bill
Thank you Bill - I am having trouble finding the _data folder. All I can find is a folder with the .aup files 
The _data folder and the .aup file will have the same name. For example: “myproject.aup” and “myproject_data”. Try searching your hard drive for the aup file name. If you find any, move the _data folders into the same folder as the .aup files.
– Bill