Boot failure

Hi. So I’m in the boot menu trying to boot from a flash drive that has a malware removal program on it and my keyboard is suddenly not responding where you are asked to enter a choice of “USB boot options”. It was working for the previous question where you enter a choice of type of device,or other means, you want to boot from. I got the flash drive at Newegg, I don’t know if it is bootable, I’m trying to bring up Windows XP. I need to rescue my computer.What do I need to do? Thanks.
OK I tried again and this time I was able to make a choice of USB boot options but I got “failure to boot” and “Non-NTFS partition or encrypted disk detected”. Does this mean I have to make the flash drive bootable? Thanks