Can I ashamed for having 3 year gap after 12th and now I want to join collage
There is no need ashamed for dropping three year, aspirants in different feild can take 3-4 years or more drop to preparing for their individual goals .
So, Be confident about what you are doing and if you wish to take admission in B.Tech go ahead in your life.
I hope you will take admission in the prestigious college recently. Have a great future waiting for you ahead.
First of all, delete this ashamed word from your dictionary. Our youth of country like you should not have these kind of negative thoughts about themselves in any situation.
There is no need to be ashamed for joining college late. The good thing is even after such long time, the spark to study and shine once again is still there in you and believe me that's not ordinary. People loose path in these time. But you took a step towards this courageous decision. By mere this decision, you can be inspiration to other people who left their studies due to some reason and didn't did just because of having hesitation and this social stigma of being ashamed.
I have personally seen very old age people who enroll themselves to study. When they can do , how you can't??. You can definitely do that. See people always judges you no matter you do good or bad. When you do bad, they will leave. When you do good in the same thing, the same people will come along and congratulate you. So are going to put your studies and your life just because of those worthless judgments. I don't think that they worth it.
Just don't think anymore and go for it, rest leave in the hands of god. Everything will going to be in favour of this courageous boy naming Ajay. And no one will be able to stop him.
If any query please do comment/post. I will be glad to help you out
Warmest best wishes

Best of luck
There is nothing to be ashamed of their are people who take a gap of five years so don't worry and get a college of your own choice.
Hope your doubts are clear now.
Good luck