I would disagree with Larry, that floppy drives frequently break. It rather depends on usage, and generally now they are not used that often.
Often problems are caused by a build up of dust and fluff. To clean means removing the covers of the drive. etc.
However you advise yours is not being detected. As a first step I would check the bios to see it is enabled, then disconnect/connect the drive's power and interface cables (possibly at both ends if there is a connector present).
Please advise back on progress.
Good Luck - Keep us posted.