Did you crank it down until it felt like it would break? That's how I ruined my kitchen faucet last year. You get desperate and think more force is the answer, but it just cracks the plastic inside. My advice is to shut off the water and take the handle apart to see what's busted. If it's the cartridge, you can get a new one for cheap, but you have to match the brand. Otherwise, you'll just make it worse and end up with a bigger mess.