For something to be bootable, your computer has to be able to boot from it instead of the hard drive. Normally, a boot disc would be the most preferable option for bootable media (either a floppy, CD or DVD), but with the growing popularity of USB flash drives, people are using those to boot their computers when their hard drives fail or do not work for some other reason.
Insert a floppy disk into your floppy disc drive, and click on "Start" and then "My Computer."
Find your floppy disc under the words "Devices with removable storage." Right-click on it and select the "Format" option. Check the box next to the words "Create an MS-DOS Startup Disc."
3.Click on the "Start" button and wait for Windows to create the MS-DOS startup disc. When it tells you the operation is complete, insert your USB flash drive and exit out of any auto-play options that appear.
Navigate back to "My Computer" and find your floppy disc again. Double click on it and a window will appear, showing the contents of your disc. Press "CTRL + A" to select all the files, then press "CTRL + C" to copy them. Navigate back to "My Computer" and find your USB flash drive under the words "Devices with removable storage." Double click on your USB flash drive and a window will open displaying the contents of your USB flash drive.
Right-click in any empty space of the window displaying the contents of your USB flash drive and select "Paste" from the menu that appears. Windows will now copy the files from your bootable floppy disc to your USB flash drive, making it bootable. You can now use this drive to boot into your computer if something happens to your hard drive.