From your JSFiddle - I think this is a simple mistake. you wrote
formDel.hidSoundeFileName instead of formDel.hidSoundFileName
remove the redundant "e" and you should be fine.
below is my working example. let me know if I missed something.
<!DOCTYPE html>
<html>
<head>
<script type="text/javascript">
function copyEditDeleteSongFormData(formDel, formUpd) {
formUpd.txtTitle.value = formDel.hidTitle.value;
formUpd.fileSoundFileName.value = formDel.hidSoundeFileName.value;
formUpd.txtCount.value = formDel.hidCount.value;
formUpd.txtTitle.value = formDel.hidTitle.value;
}
</script>
</head>
<body>
<form action="adminSong.php" method="post" name="frmNewUpdateSong" id="fUpdateSong" enctype="multipart/form-data"
onsubmit="return verifySongDetails(this)" action="adminSong.php">
<fieldset>
<legend>New/Edit Songs</legend>
Artist
<br>
<select name="cboArtist" id="ddList">
<option value=''></option>
<option value='test1'>test1</option>
<option value='test2'>test2</option>
<option value='test3'>test3</option>
</select><br>
Song
<br>
<input type="text" name="txtTitle" id="txTitle">
<br>
<input type="file" name="fileSoundFileName">
<br>
<br>
Count
<br>
<input type="text" name="txtCount">
<br>
<input type="submit" name="btnSave" value="Save"/>
<input type="button" name="btnReset" value="Reset" onclick="resetNewUpdateSongFormData(this.form)"/>
<br>
<input type="hidden" name="hidId">
<input type="hidden" name="hidSoundFileName">
<br>
</fieldset>
</form>
<br>
<form action="#" method="post" name="frmEditDeleteSong" id="fDeleteSong" enctype="multipart/form-data">
<fieldset>
<legend>Stored Songs</legend>
id: <br/>
artistid:<br/>
title:<br/>
sound:<br/>
count:<br/>
changedate:<br/>
<input type="hidden" name="hidId">
<input type="hidden" name="hidArtistId" value="">
<input type="hidden" name="hidTitle" value="Songtest">
<input type="hidden" name="hidCount" value="Count123">
<input type="hidden" name="hidSoundFileName">
<br>
<input type="button" name="btnEdit" value="Edit"
onclick="copyEditDeleteSongFormData(this.form, frmNewUpdateSong)"/>
<input type="submit" name="btnDelete" value="Delete" onclick="verifyDeleteOfSong(this.form)"/>
<br>
</fieldset>
</form>
</body>
</html>
copyEditDeleteSongFormDatafunction in lineformUpd.fileSoundFileName.value = formDel.hidSoundeFileName.valueas it is unable to find that element. If you move this line as the last line of the function your code would work. If you check the errors in error console in any browser you would be able to see all the errors. I have removed some errors in this fiddle. jsfiddle.net/mVfZa/8