Why won't my code run, it runs fine till I added like question 3 and above.....

You have a few errors which is why it isn't running.

Firstly, if you go to your 'index.html' file, you have the 'quiz.js' script added to the page twice. You should remove the top one and move the one near the bottom so it is just above the closing </body> tag, rather than inside the .container div. Having it on the site twice means the script is running twice.

You also have a few syntax errors in your quiz.js file. If you go to the page in your browser and look at the developer tools, it will tell you which lines these are on and what the errors are.

On line 75, you are missing a closing bracket after '( month and year?'. It should be ( month and year?)

Then further down the file you have assigned a value to your medal variable using document.write. However, you just want to assign a value to the variable and not the document.write method. You are outputting the value of the medal variable to the page using the document.write method later in your script on line 105.

Also, in this block of code you are using:

if(score === 100) {
    var medal = document.write(<h2>GOLD?</h2>);
} if else(score === 80) {
    var medal = document.write('<h2>SILVER ?</h2>');
} if else(score === 60) {
    var medal = document.write('<h2>Bronze</h2>');                           
} else {
    var medal = document.write('nothing');
}

However, the statement should be if, else if, else so:

if(score === 100) {
    var medal = 'GOLD?';
} else if(score === 80) {
    var medal = 'SILVER ?';
} else if(score === 60) {
    var medal = 'Bronze';                           
} else {
    var medal = 'nothing';
}

Once these errors are fixed, your quiz should work.

Hope it helps.

EDIT.

To make the last bit of code a bit cleaner, you should also declare the medal variable at the top of your script as you have done with your other variables.

    var medal;

Then your last bit of code could just be written as:

if(score === 100) {
    medal = 'GOLD?';
} else if(score === 80) {
    medal = 'SILVER ?';
} else if(score === 60) {
    medal = 'Bronze';                           
} else {
    medal = 'nothing';
}