If you were logged in when you started your order, your basket will have been saved. Simply log in, go to My Account and click on Previous Baskets. From here you can reload your basket and proceed to the checkout, or carry on shopping.
If you have lost your connection and then come back on to the website, you will be prompted if you were halfway through a basket before being cut off, allowing you to resume from where you finished. This does depend on your computer set up and whether you have cookies enabled.