Hi:
You have two choices...
1. You can click on the Update Now button at the link below to reinstall W10.
2. You can download the W10 ISO file by using the Media Creation Tool below, and make your own W7 installation/repair disk or USB flash drive.
https://www.microsoft.com/en-us/software-download/windows10
Then you need to use the ISO to DVD/USB tool to transfer the file to a USB flash drive.
https://www.microsoft.com/en-us/download/windows-usb-dvd-download-tool
The tool will make the flash drive bootable.
Then you can reinstall W10.
When you get to the part during the W10 installation, where you are asked to enter a product key, you select the 'I don't have a product key' option, and W10 will install and automatically activate once you are connected to the internet.