Audacity Forum

I can't open files made with audacity:

error: can't find the projects datafolder: "röstprov karolina_data"

if the data folder got deleted there is no fix unless you can undelete.
if it got moved then move it back
(or edit the name in aup to point to where it is now)
if the aup folder got move then move it back.

Someone else made the file and sent it to me

You need to have both the AUP file and the data folder and they must both be in the same directory.
See here for an explanation of how Audacity handles files and projects: http://wiki.audacityteam.org/wiki/File_Management_Tips

It is much easier to send data as an audio file rather than as an Audacity Project.
Ask them to "Export" the project as either a WAV (high quality but large file size) or as an MP3 (smaller file size but lower quality).