javascript valiadtion problem

Try like this. this one is simple.
function validateForm()
{
var Firstname = document.getElementById("txtFname").value;
var Lastname = document.getElementById("txtLname").value;
var Username = document.getElementById("txtUserName").value;
var e = document.getElementById("ddlUserRole");
var Role = e.selectedIndex;
var currentProject =document.getElementById("lbCurrentProject").value;
var Password = document.getElementById("txtPassword").value;
var Confirmpassword = document.getElementById("txtConfirmPassword").value;


if (Firstname == "First Name" || Firstname == "")
{
alert("Firstname must be filled out");
return false;
}


if (Lastname == "Last Name" || Lastname == "")
{
alert("Lastname must be filled out");
return false;
}


if (Username == "User Name" || Username == "")
{
alert("UserName must be filled out");
return false;
}

if (Role == 0 || Role == "")
{
alert("Select your role");
return false;
}

if (currentProject == null || currentProject == "")
{
alert("Select your current projects");
return false;
}

if (Password == null || Password == "")
{
alert("Password must be filled out");
return false;
}
if (Confirmpassword == null || Confirmpassword == "")
{
alert("Confirmpassword must be filled out");
return false;
}

if (Password != Confirmpassword)
{
alert(" Passwords must match");
return false;
}

//alert("You are registered successfully!!!!! Login Now....");
return true;
}

Use this function
function IsNumericOrCharacter(strString)
{
//valid string
var strValidChars = "0123456789.-~`@#$%^&*(){}[]:;'<>? ";
var strChar;
var returnResult = true;

if (strString.length == 0) return false;

// test strString consists of valid characters listed above
for (i = 0; i < strString.length && returnResult == true; i++)
{
strChar = strString.charAt(i);
if (strValidChars.indexOf(strChar) != -1)
{
//document.getElementById('+ id +').value="";
alert("Numeric or special characters or spaces are not allowed");
returnResult = true;
}
}

return returnResult;
}