IÂ´m not sure why the set-up doesnÂ´t work.
I do this quite often, so if you donÂ´t mind, IÂ´d like to just go through how I do it , in case we have missed something.
Cassette player is on...and everything is the right way around (tape recording is able to be heard when you push play etc)
Audacity is running on the PC
You have connected the headphone output of the cassette player to the microphone input of your PC, with a double ended 3.5mm plug/cable connector.
You have selected microphone as the source in the Audacity window
You have adjusted levels of the cassette player output (around 3 on a scale of 10)
You have adjusted levels of the microphone and speaker controls on the Audacity interface (Mic at about 2, and speakers at 5)
The audio should be visible in the level meters...adjust to avoid going too high (donÂ´t go into the red)
Click the big red record button on Audacity
ThatÂ´s about how it should work.
If you have checked every aspect carefully...and it still doesnÂ´t work, then the quickest and easiest solution is to try this on another computer. Perhaps a friend will let you try it.
Try it all again and let us know what happens.