Thanks. I looked into the tutorial and also did some Google searches. Many results are related to create a system repair disk but finally got a video on you tube.
It is actually quite simple:
1. Format the flash drive with NTFS, then copy the contents of the system repair disk to it. The ISO image of the system repair drive can be found from the Internet.
2. In Command Prompt type "diskpart"
3. Type "list disk"
4. Type "select disk x", where x is the number of the flash drive listed by "list disk"
5. Type "list partition"
6. Type "select partition x"
7. Reboot and use BIOS setting to boot the system repair flash drive
Sorry for the trouble. I should have searched information with more patience.