Hi @gabrielmeir53 ,
Have you tried a different floppy disc, just in case the one that you tried is faulty?
Check that the floppy drive's data cable is connected securely to the motherboard and to the floppy drive. (is it a 3.5" drive or a 5.25" drive?)
As it hasn't been used for a long time, you may have to clean the read/write heads in the drive.
Here is a link to a video that shows how to clean the R/W heads in a 3.5" drive
As mentioned in the video, use IPA 90%+ (Isopropyl Alcohol - available at most pharmacies) to clean the heads.
If your drive is a different type to what is shown in the video, search You Tube for "clean 3.5" (or 5.25") floppy drive heads" that may show how to open and clean your particular type of drive.