Ubuntu 14.04 64-bit stuck on the purple screen that shows the word Ubuntu and loading. Nothing happens after that. I tried to use a flash drive with Windows 10 to remove Ubuntu and install Windows, but when I press F9 and select the flash drive it does nothing and enters the normal boot of Ubuntu. I have checked the boot order in BIOS.
Is this a new installation or was it working before?
When you enter the BIOS have you checked that the RAM is detected? It can be one of the problems. I would try to clean the ram with an erase. Maybe your team is already somewhat old.
This YouTube video shows how to clean your RAM.
Have you made any changes to the equipment? The more information you provide, the more we can help you.
Have you changed the boot order in the BIOS? This is found in the "Advanced options" or "boot" tab and with the options there you may have to put USB devices first.
Have you checked that the Windows flash drive works on another computer?
Have you made the flash drive in NTFS file format? If not, you will have to format it from Windows file explorer.
If the flash drive does not work try to do it with the Rufus application.
Here's a YouTube video on how to make an iso with Rufus.
If you want Windows 10 you can do it without Rufus and without any .iso and do it with the tools that Windows gives. See this page on microsoft.com for details.
Edited 2: have you tried another usb leek? Sometimes, despite having performed all the steps correctly, the PC cannot start from the USB. Usually, some PCs need to have the "USB Legacy" option enabled in the BIOS.
You must enter the bios and look for an option called "USB Legacy" or "Legacy USB support"