Experience once that my heart stops its beat for a couple of seconds . Is it a sign of a heart failure ?

It might just be a mild form of Arrythmia. Sometimes, if your heart skips a beat, it seems like it stops completely. But, it's not possible because that means you'd already be dead. LOL! Kidding aside, though, an ECG is your best choice in order to know exactly what your heart rhythm is and if it's normal or not. Hope you feel better!

That's scary bro. Have your checkup at once. Better to be sure than sorry.