Hi is there anyway I can export an audio file that is 24 hours long please help
You need to use a format that supports recordings that long, and storage that has space for and support for such a big file.
OGG Vorbis or MP3 should work, provided that there is sufficient disk space.
Alternatively, you could split the recording into multiple files using “Export Multiple”. See: https://manual.audacityteam.org/man/export_multiple.html