Can i upgrade my windows 8.1 with downloaded windows 10 ISO file. i have windows 8.1 (single language) installed in my laptop and i downloaded windows 10 (home single language) iso. can i upgrade my window 8.1 with this iso without losing my windows key. or i need to upgrade from windows server and after upgrading can i do a clean install with this windows 10 iso.
Yes you can update from the ISO. Also you will be able to do a fresh install, but you need to upgrade first. When you do a fresh install just skip the key part. Use windows media creation tool to upgrade/download the Win 10 ISO.
You must upgrade to win 10 and with the same version you have now, IE home, pro an so on. Once you upgrade and it's activated, you then can clean install win 10 with same ISO, but you don't add any key when installing, just install and skip when asked for key. You can boot from the ISO or just extract the ISO on your desktop and run setup, either way to upgrade.
You need same version of windows 10. You have a single language 8.1 so you also need to get an ISO that is Windows 10 Single Language to do the upgrade.