When your clutch pedal is dropping down and not coming up again, the cause is most probable one of the cylinders in the hydraulic clutch system. The video will give you a step-by-step tutorial on how to replace both, the master and the slave cylinder. In addition, it is a good idea to also replace the pressure hose in-between the cylinders.
The video is made using a Porsche 944, but the repair is quite similar for all cars, having a clutch hydraulic, operated with brake liquid.
After opening the clutch system, it is necessary to bleed the system. The video presents a way to perform this without expensive special equipment, by just modifying a brake reservoir lid with a tire valve and using a standard compressor to press the new brake liquid in and the air out of the clutch system.
The video has a German soundtrack, but English subtitles are available by clicking on the "CC" to turn on YouTube's captions.