My mac is completely blocked

Best thing to do is to take the computer to the nearest Apple store and have it checked out.

A Mac is in limited warranty for 1 year from the date of purchase.

Best.

...Even the clock has stopped.

This suggests that you can see what's on the display but can't do anything. If so, hold the power button for about 10 seconds to force quit the computer. Then press it to restart the computer.