If there is no data on hdd you need to recover (other than hidden factory recovery partition) try to build a bootable usb on another pc by using Microsoft Windows 10 download media creation exe.  USB size needs to be greater than 4GB.  When done use it to start a clean install of Windows by pressing F12 and select boot from USB, proceed to install, during install choose custom option, delete old OS partition on hdd, but do not delete factory recovery partition on hdd.  create new partition, format it, hit enter to let it install.
Hello, my OptiPlex 7070 (Win10 Pro) does not load windows. The startup Repair tool does not solve the issue.  When I try System Restore, I see the restore points. However, when I choose any of them, I am not able to select the drive and get "You must enable system protection on this drive"  I downloaded the Dell OS Recovery Tool to another PC to create a bootable USB. However, when I entered my Dell' tag number, I get "Recovery image currently unavailable". I also tried SupportAssist OS Recovery tool. Turned PC on, F12, connected to the internet and downloaded successfully. Automatically started SupportAssist but did not open. Ended up with blue screen (error 0xc0000001). Runned all SupportAssist Pre-Boot System Performance Checks and all came out OK.  Not sure where to go from here.  
Blue screen error code 0xc0000001 on OptiPlex 7070 running Windows10 Pro