Hi guys need your help and suggestion,
I am a male, 31 years I had a manager of the age 36 in earlier company and we had a good profestional relationship... I left that company and joined a new one, I came to know that my manager lost her husband in an accident, after that she tried to avoid most of them in the office and after 2 years she joined the company that I am presently working.
She contacted me and we came to know that we sit on the same floor, we used to go for Breakfast and lunch together most of the times, one day she came and told me that she liked me and would like to be in a serious relationship with her and she wanted to know my answer soon with in a week.

Initially I could not digest the fact, as I always took her as my mentor and a mental support always, now to change my thinking it was difficult and I was a bit tensed about it. But gradually I started thinking in that line, and started developing liking for her.

She used to come very close to me which I initially hesitated to.
But after some days she took a step back and told me that I was not the right person as I am not matured to handle this relation, I'm too emotional, I don't understand thinks quickly and all, and she wants to backoff and started ignoring me.

Now I am in a state where I started thinking for her a lot. I have developed a strong feeling for her, I don't know what to do.

I have lost a good friend, a mental support. And now the love that I had for her that too... what's was my mistake in that.
Please help me on this how to handle the situation and if possible can I get her back as what she used to think initially for me.

She might have just been hurt by your first reaction, and you should go all out explaining that you were confused and have grown to like her very much. Bring her flowers, be glad to see her, tell her you really want to try. (I can see how her cold approach would be a turn off though - wanting an answer in a week sounds like a boss ordering an employee around.)

Yes, what you did was reject her, she is hurt and you need to go and be totally honest with her NOW, the longer you wait the more pain that will be there.

I don't understand, 5 years difference, you act like she is a old lady or something, at 30, 5 years is notihing, that is considered close to same age.

If you viewed or judged her differently, that is your issue. And she is right,