Windows 10: upgrade from windows 8.1 professional to windows 10 professional without losing data

I have a desktop with windows 8.1 professional 64 bit license OS installed. I have to upgrade it with windows 10 professional . Is it possible to upgrade it without losing applications and data? I don't want to format my HDD.thanks in advance.

:)

 

Using Windows 10 Professional Product key to Windows 8.1 Professional

HI,

Due to some inconvenience while using Windows 10 Professional, I want to use Windows 8.1 Professional.

1. Can I use the Windows 10 Professional product key to activate & use Windows 8.1 Professional?

2. As I have already purchased Windows 10 Professional License, don't want to pay again for Windows 8.1 Professional.

Please Suggest...

Thanks..

 

Windows XP professional

I am having problems with my PC. The system started rebooting while I was trying to login yesterday. Since then, the system boots up till the Windows XP logo is displayed and starts rebooting. When I tried to go to "Safe Mode" the process stops at "Partition c:\Windows\ststen32\Drivers\Mup.Sys" and starts rebooting. This loop goes on.

Can any one suggest how to repair/reinstall the XP professional edition.

 

Upgrading Windows 10 Home Single Language to Windows 10 Professional using Windows 8 Professional key

Hi. I had purchased a Dell Inspiron 7559 that came with Windows 10 Home Single Language preinstalled. I had previously purchased Windows 8 Professional and have got the key for it. Can I use that key to upgrade the Windows 10 Home Single Language in my
Dell to Windows 10 Professional? Is there any specific method to do it or is it as straightforward as Settings > Update & Security > Activation > Change product key and then enter the Windows 8 Professional
product key to proceed with the upgrade?