No, formatting D: will not affect your C: drive.
If it is a "few days old" computer, you should take it back to the store. There is no good reason for the d: drive to be reset like that.
Here are some links on how to get the Windows 10 installation tools and files for from MS for free.
WINDOWS MEDIA CREATION 10 – CURRENT WIN10 DOWNLOAD – WIN10.ISO
https://www.microsoft.com/en-us/software-downlo...
Download and run the media creation tool to get started. For more information on how to use the tool, see the instructions below. Downloads the “most current” ISO, but there is no indication of what version it is.
MEDIA CREATION ERRORS – DAVE M’S FIX
A solution to this that has worked for many users is as follows:
Download the Media Creation tool onto the same USB flash drive that you intend creating the bootable Installation media onto.
Then run the Media Creation tool from that USB flash Drive . . .
A strange solution, but seems to work . . .
GREG C’S CLEAN INSTALL TIPS
Greg’s Wiki is a very comprehensive set of suggestions and instructions to follow when doing a clean install.
https://answers.microsoft.com/en-us/windows/wik...
create Windows 10 installation media (on a USB stick) or download a free ISO file https://www.digitalcitizen.life/how-download-wi...
http://www.zdnet.com/article/hands-on-with-wind... - ZDNet How to install, reinstall, upgrade and activate Windows 10
https://www.digitalcitizen.life/how-install-win... - This article has lots of pictures.
https://www.microsoft.com/en-us/software-downlo... - Media Creation Tool, Download CURRENT version ISO
https://www.intowindows.com/download-windows-10... - Download ISO without media creation tool
https://www.heidoc.net/joomla/technology-scienc... Heidoc Microsoft Windows and Office ISO Download Tool – Download older versions of the iso
2017 10 25- CREATE BOOTABLE USB DRIVE
https://www.groovypost.com/howto/create-windows...
Although the page refers to “Windows 10 Technical Preview” you can use any “ISO” (Windows installer file). Greg C’s instructions tell how to download the current ISO.
HOW TO INSTALL WINDOWS 10 FROM USB WITH UEFI SUPPORT
https://www.windowscentral.com/how-create-windo...
If you have a PC using UEFI (Unified Extensible Firmware Interface), you can use these steps to properly create a bootable USB media to install Windows 10.
https://www.youtube.com/watch?v=iosA3Bn9RMI
2018 08 02- INSTALL WINDOWS 10 USING A DVD/CD, AN ISO FILE OR A FLASH DRIVE
https://www.digitalcitizen.life/how-install-win...
In this guide we show you how to make a clean Windows 10 installation on your computer or device, using the following types of installation media: DVD, CD, ISO file, or USB memory stick.
USE RESET TO RESTORE YOUR WINDOWS 10 PC - FREE DOCX/ EBOOK DOWNLOAD
http://ligman.me/29yWAAO
**************** "Disclaimer" **************
We are forced to include this Standard boilerplate legalistic bafflegab disclaimer for any links to non-Microsoft websites:
(Short form: use these links at your own risk, just like everything else from MS!)
The link(s) to non MS-page(s) appears to be providing accurate, safe information. I suggest you stick with the “manual” instructions. Unless I explicitly suggest it, avoid downloading their “utilities”. Thoroughly research any product advertised on the site before you decide to download and install it. Sometimes they include 3rd party programs, "unwanted" programs that are automatically installed during a standard install. So, if offered, do a "custom" install and carefully read each step. One of the steps MAY give you an option to install, or NOT, "additional" programs. 99.9% of the time you don't want to let them be installed. For example, when you install Adobe Player you are given the option of installing 2 additional "free trial" programs: Potentially Unwanted Programs: MacAfee Security Scan and MacAfee Safe Connect. The option to install is turned on, you have to manually turn it off. Those are PUP's. If you click "OK"/"Next" without paying attention you get the 2 "extra" programs.
As well, watch out for ads on the site. They may advertise products that include PUPs. Thoroughly research any product advertised on the site before you decide to download and install it.
************* End BS Disclaimer ************