I can't open any audio file and can't record from mic

[freeflydream]

when I open an mp3 file, Audacity shows the progress well. But after loading file, there is nothing in the Track Panel, and no blue wave lines.
When I try to record from mic, the Track Panel show some blue wave line, but once I stop recording, all the blue lines disappear!
Then of course I can't play and export any sound from there.


I have no idea why it doesn't work.
But when I just installed it in my computer one hour ago, it worked well and I actually have opened a mp4 file and exported its audio to an mp3 file.
Now it can't work.

Who can help me solve this problem??

[steve]

Are you logged in as the same user as you were when you installed Audacity?

It sounds like the Audacity temp folder is located somewhere that you don't (with your current log-in) have permission to write to.
You can check the location of the temp folder by looking in "Edit > Preferences > Directories".