To perform a full sector by sector backup of your hard drive, if you are part of an organisation with an IT department, ask if they have any software to be able to perform this task.

Alternatively, if you are a home user or you are part of a smaller organisation, you can download free trial versions of the following software to enable you to perform this task;

Acronis

http://www.acronis.co.uk/homecomputing/products/trueimage/

O&O

http://www.oo-software.com/en/products/oodiskimage/index.html?r=s

Paragon

https://www.paragon-software.com/uk/downloads/demo.html

Details on how to use each of these vary and therefore it is recommended that you follow the instructions for the relevant software carefully.