If it happens with only 1 floppy and others are OK then duff floppy.
If it happens with all floppies then duff drive.
I have occasionally found that a temporary expedient of "adjusting" the position of the floppy with my finger (ooer missus) can help to read data off a floppy, but this is usually when alignment is out.
Floppy drives are incredibly cheap, though, except for Compaq which are unique and 10 x times standard price. Almost always very easy to replace if you are happy opening up the case. Otherwise bring it to a high street specialist.
SD