Check your clutch fluid reservoir under the hood, on the drivers side next to the brake master cylinder. If the fluid level is low, then air may have entered the system causing a lack of hydraulic pressure needed disengage the clutch. If this is the case, topping up the reservoir (with brake fluid) may allow some of the air to escape, but you will have to pump the clutch pedal several times to achieve this. I only say this because it has worked for me before.
If air in the system is definitely the case, then properly bleeding the system from the bleeder screw on the transmission itself would be recommended.