The 1073 is the lumia 640 afaik and I don't believe it has a dedicated camera button, which means that the hard reset button combo would not work for you..
Use the Windows Device Recovery Tool to reset your device. This will take you back to the OS version which originally came with the phone. So for phones that did not ship with W10M, the WDRT will take it back to 8.0. If the phone was shipped with W10M, the tool will take it back to a version of W10M
Follow this link for instructions and download: http://www.microsoft.com/en-us/mobile/support/faq/?action=singleTopic&topic=FA142987
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