I have tried several tools (apps, books, ....). They sounded easy in books, paper and web. In reality not so.

What is distracting you in the first place? Best way is to simply disconnect the internet and turn off the music. Try using Freedom for disabling internet. Have you tried using the Pomodoro technique?

1. decide on the task to be done
2. set the pomodoro (timer) to 25 minutes
3. work on the task until the timer rings
4. take a short break (3-5 minutes)
5. every four "pomodori" take a longer break (15–30 minutes)

30/30 for iPhone and iPad is great for that.

I agree w/ @LukaMarcetic in a slightly different way. I've been trying to design entire websites / application interfaces against completely unrealistic timelines just to see what really is possible. I've found that it's easy to procrastinate with creativity because it isn't "procrastination" if you're looking for "inspiration" or waiting for that thought-provoking bolt of genius-lightning. I've noticed that if I block everything out and give myself 1 hour to finish a complete UI design, I don't succeed but that pace continues and I have something to critique within 3 hours. Then step away and get feedback, lunch or work on something else... then jump back in just as hard. Apply the P90x approach to everything.

@LukaMarcetic Most of the time, i am distracted because of distractions. (Somebody will call my office extension / Somebody walks in to my office / I am too bored to concentrate on a work which requires lot of concentration.....)
I will try 30/30 app. I have tried several other apps like "Orchestra" "Wonderful Day" and I lost track of them after a month.