2 Answers

1. Did you increased the size of your page at some point? The page could be too big for your computer screen. To resize your page go to your start button > control panel > appearance and personalization or themes > adjust screen resolution. There you can make the screen smaller.

2. Did the page shift so it's too far right? You can place your cursor at the very tip top of your page and left click hold and move the page to the left to see if the scroll bar is there just off the screen. If this is the case, set the page so you can now see the scroll bar. The text on the page may now be too far left so it is cut off. In this case, you would move the page back to where it was when the scroll bar was missing. Then place your cursor on the very left edge of the page. When you see the double ended arrow appear, left click and hold and drag the edge of the page right approx the amount you need to move the page over to show the scroll bar again. Once you've done that, go back to the tip top of the page, left click and hold and move the whole page left until you see the scroll bar. 

You go me on that one, sorry.

No matter how large I make my screen I still have the side slider.

Try using the scroll wheel