Broken clutch fork or hydraulic line if a hydraulic clutch.

The clutch is not adjustable.

Clutch disc is worn out. Not knowing what vehicle you have, most are hydraulically operated and there is no adjustment. Time for clutch replacement.

If it's a hydraulic clutch, try bleeding the slave cylinder. Manual linkage, try adjusting the clutch. If no help, something's wrong with the pressure plate and you need a new clutch.

check your clutch fluid level and your clutch slave cylinder for leaks,if both are ok,then you probly need a new clutch.