I have been using Sound Forge for some years. I have tapes and otherwise analog recordings of audio I record onto my computer as WAV files by plugging the tape player (or otherwise) into the computer's line in jack.
I was attempting to do the same tonight. I hit record and no sound occurs, the meters on the Sound Forge recorder do not "dance". So I check the recording mixer, and it is set to "line in" and an appropriate level. I am hearing sound when I engage "line in" on the playback mixer but it is not registering for recording.
My first thought is, oh crap I fried my soundcard. When I first turned the tape player on, it's volume was rather high (I'm coming out of the headphone jack) and there was a good deal of distortion.
HOWEVER I then tried to record with the little dinky Windows "Sound Recorder" and, guess what, it worked perfectly.
WHY would it record well in Sound Recorder but not in Sound Forge? For the record, when I crank the line in record lvel, and the volume on the tape player, and record in Sound Forge, it records both very faintly, and distorted. Like it's muted somewhere.
I'm not familiar with Sound Forge. Might be an additional place to select line-in as the source and / or control recording level within Sound Forge? If not... reinstalling the software may do the trick. Would try uninstalling it, deleting any files left in the programs folder after the uninstall, and reinstalling it after a restart.