need a reliable program to make an image of my hard drive asap ( immenint failure )

so I got the immenent failure error message and I need to make a backup img of my hdd so that I can send this hdd to HP and get it replaced but I'm lookin for a reliable program to make a img that i know will work. I got all my info on an external hdd but theres just so much organizing that i'd have to re do and much much more.