How can I burn a copy of the Windows 8.1 ISO that came installed on my laptop?
Use free CDBurnerXP software from https://cdburnerxp.se/en/home and supports Operating Systems: Windows 2000/XP/2003 Server/Vista/2008/Win7/Win8 (x86 / x64)
CDBurnerXP is a free application to burn CDs and DVDs, including Blu-Ray and HD-DVDs. It also includes the feature to burn and create ISOs .
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Assuming your optical drive is capable to burn CD/DVDs just right-click the ISO file and select "burn disc image". Windows 7/8 can handle these by default.
You will find detailed instructions here: