bad secotrs on floppy disk

I have 2 floppy disks that have bad sectors on them. How can I remove them? I also have 3 othere floppy disks and they are 720kb capacity and the problem is that I cannot see what is on them or even format them. They have only the one small sqareat the top right of the disk instead of the 2 holes. Does this matter? How can I format them to use again?