Manuals for digital multimeters are available on the official Innova, RadioShack and Extech websites, as of 2015. These websites offer owner's manuals for many different digital multimeters.
Visit Innova.com, click the word Products in the top menu and then click Digital Multimeters in the list of options. Click the Detailed View link for the appropriate model and the product Web page appears. Then click the Download Manual/Software tab. Click the Manual File icon and the owner's manual appears in the browser window.
Visit Extech.com, click the Instruments image and then click Multimeters in the menu located along the left-hand side of the Web page. Select Digital Multimeters from the options list. Choose the link for the appropriate model. The link for the manual is located under the Downloads and Software heading of the Web page.