If your PC doesn't have an optical drive or doesn't have a DVD, the best solution is a bootable USB drive. After all, a USB flash drive is portable and you can make sure it is compatible with all desktop and laptop computers. While some computers may don't have a DVD drive, all of them have a USB port. It is also faster to install from USB. A USB drive can boot faster than an optical drive.
Steps to Install Windows 10
Before moving to steps in order to install Windows 10 from USB, you need a device with at least 8 GB of memory. Before continuing, make sure the USB flash drive has been formatted. Keep in mind before downloading a bootable Windows installation iso image file, it is important to know the difference between UEFI and BIOS.
Old PCs work on BIOS i.e Basic Input Output System to boot the operating system and manage data between the operating system and devices. UEFI stands for (Unified Extensible Firmware Interface) has replaced the BIOS, adding legacy support. UEFI can help with PC diagnosis and repair without software or additional means.
The bootable flash drive supports UEFI hardware and legacy BIOS. Therefore, the option you select will work for your PC.
> Set the preferred language of yours, Windows 10 Edition, and system architecture. If these settings cannot be changed, you must clear the Use recommended options for this PC checkbox. Press Next again.
> Select the USB flash drive, then Next, and select the USB drive from the list. Click Next once again to request the download of the Windows 10 installation files.
[Note: You can also use a third-party tool for creating bootable Windows installation media if you have an ISO file already downloaded then only or you can download it by selecting 2nd option shown above. I will recommend Rufus, it is a great tool].
Wait while the Windows 10 USB boot installer is being created. How long will depend on the speed of the Internet? Several GB's of data will be installed, so if you don't have access to a fast Internet connection consider a library or even your workplace with high-speed WiFi access.
Once the installation media created, you will be able to install Windows 10. The USB drive is now bootable, so all you have to do is safely remove it from your PC and then insert it into the target device.
> Turn on the computer you are installing Windows 10 on and wait for it to detect the USB drive. If this does not happen, reboot, this time by pressing the key to access the UEFI / BIOS or the boot menu. Make sure the USB device is detected, then select it as the primary boot device in the option "Boot Priority" which can be found on the UEFI/BIOS menu.
[Note: Accessing UEFI/BIOS is different for every laptop or desktop as is configured by the manufacturer.]
> The next reboot should detect Windows 10 installation media asking press any key to boot from USB.
[Note: In some laptops, you will find secure boot is enabled error, then in order to solve it you have to access BIOS menu & in advanced options turn off the secure boot & then restart. It will work. Actually, secure boot is enabled on pre-installed windows in that case manufacturer provides recovery partitions in case of any failure you don't have to follow complex steps for windows re-installation just go to start & search reset this PC & start the process & done. Your PC will automatically restart & replace the previous windows, only C drive gets affected until & unless you choose the Advance option for PC recovery].
> Make sure you are connected to a stable power source before continuing the installation process or at least 90% of the battery in case of laptops, if not done your PC may cause malfunction.
> Start by starting the installation wizard, click Next after that Install Now. Don't click anywhere else.
> It may ask you to enter the product key, enter it if you have or else you can skip & do the activation later. In the case of laptops that come with Pre-installed windows, activation will be done automatically after connected to the internet once the installation is complete.
> Accept Microsoft license terms then proceed to the next step & click Custom.
> In the next step, a disk partition screen will appear where you can delete the existing partition or create a new partition.
> Partitions system reserved partition is invisible you can't see it on This PC or my computer as it is only for the system itself.
> To make you an expert on windows formatting & disk partitioning, first of all, I will explain how to split an already created partition & please beware doing this on windows setup will definitely clear any data on the particular partition so if you have anything there I suggest you to back it up before doing this.
> Delete all partitions if you want to format the whole computer by selecting the partition individually or else if you only want to format 'C' drive only & keep rest of the files then format only the 'C' drive it will be labeled as Partition 1-2-3 etc. you can figure it out by the size of the particular partitions which was created before.
> Choose the partition where windows are installed & click on delete also the system reserved partition. An unallocated partition will be created.
> Click on the unallocated partition then 'New' on bottom & after that select the size as you want or leave it as it is & create it.
> Now new partitions including some system partitions or recovery partitions will be created.
> Choose the partition which you have created & click next.
> So, now you are done, windows will be installed automatically with a couple of restarts Then you will be asked to set your PC name, password, etc. set it. After everything is done don't forget to install important drivers, all though Windows 10 comes with pre-installed drivers.
> Lastly, keep your windows up to date. Stay away from a pirated version of windows, always use genuine version.
> Note that the installation may continue after you log in, so wait. It's also worth checking for Windows updates (Settings> Updates and Security> Windows Update) after installation to make sure everything is up to date.
Creating a bootable Windows USB drive is simple:
> Format an 8 GB (or above) USB flash device.
> Download Microsoft Windows 10 media creation tool.
> Launch the media creation wizard to download the Windows 10 installation files.
> Create the installation media.
> Eject the USB flash device.
