WinME 31/2 to 51/4 need it back to 31/2

We have a PC running WinME, the floppy change from 31/2 to 51/4, and can not change back to 31/2. I think this happened when we tried to use external HP colorado back-up tape that did not work. We have unistalled colorado but still same.Tried disable floppy in BIOS then reboot, renable 31/2 1.44 then reboot same. Any idea?