There are a few reasons that your clutch may go to the floor and stay there. The most common reason is that there is a problem with the hydraulic system that actuates the clutch. If there is a leak in the system, air can get into the lines and prevent the fluid from properly moving through. This will cause the pedal to feel soft and eventually sink to the floor. Another possibility is that there is something wrong with the slave or master cylinder itself. If either of these components is damaged or not functioning properly, it can also cause your clutch pedal to go to the floor and stay there. If you're experiencing this issue, it's best to take your car to a mechanic so they can diagnose the problem and fix it accordingly. In some cases, simply bleeding the hydraulic system may be enough to fix things. However, if there is a more serious issue like a damaged cylinder, then it will need to be replaced in order for your clutch pedal to function properly again.