Couple of error in your code
<html>
<head>
<script type="text/javascript">
function validate()
{
fname = document.f.fn.value;
if(fname!= "abc")
alert("Incorrect name!");
lname = f.ln.value;
if(lname != "xyz");
alert("Incorrect Name!");
paswd = f.pswd.value;
if(paswd<8)
alert("Too short password!")
for(i=0; i<f.d.length; i++)
{
if(f.d[i].value.checked)
{
document.write(f.d[i].value);
}
}
for(i=0; i<f.c.length; i++)
{
if(f.c[i].value.checked)
{
alert(f.c[i].value);
}
}
// return false; // use this you don't want to submit form
// return true; //for advancing the form
}
</script>
</head>
<body>
<form action="" name="f" onsubmit=" return validate()">
First Name: <input type = "text" name = "fn"> <br>
Last Name: <input type = "text" name = "ln"> <br>
Password: <input type = "password" name = "pswd"> <br>
E-mail: <input type = "email" name = "mail"> <br>
Degree : <input type = "radio" name = "d" value = 's'> SE
<input type = "radio" name = "d" value = 'c'>CS
<input type = "radio" name = "d" value = 'E'>IT <br>
University <select name = "uni">
<option value = 'p'>PU</option>
<option value = 'f'>FAST</option>
</select> <br>
CGPA : <input type = "radio" name = "c" value = '3'> >=3.0
<input type = "radio" name = "c" value = '2'> >=2.5 <br>
Browse <input type = "file" name = "uf"> <br>
<input type = "submit" value = "Submit">
</form>
</body>
</html>
above code is working
I consider that you are performing validation on this form hence you need to the call the function
return validate();
Now if function return false, the form is not submitted
if function return true, the form is submitted
Do ask for further help , Don't waste my effort's