That depends. Did you have any other income (outside your business) that you need to report? If you do, then you need to file a Form 1040. And you should file your Schedule C in order to take that loss against any income you made (outside of your business.
If your sole proprietorship business has no profit or loss during the full year, it's not necessary to file a Schedule C (Form 1040), Profit or Loss from Business (Sole Proprietorship) for that year.
If your business is inactive, but you receive payments such as insurance that relate to the business, you must report those payments on a Schedule C.
Click here for additional information on entering your Form Schedule C.
Click here for additional information regarding Form Schedule C.
Click here for Publication 334, Tax Guide for Small Business.