I have learned HTML as a part of my post graduation and this is the easiest subject I found to learn and at the same time very interesting too. But after the post graduation I went for non it jobs and I never had to use these codes. When I try doing it now, I am not aware about most of the codes and really depressed. Can you suggest any good online site or community from where I can learn it again or refresh it?
My new project is <snip>
Hi, BlueLotus, and welcome to SitePoint.
I’ve moved your post to a new thread of its own. You’ll find it much easier to get help here if you post in the right section of the forums. 
If you just need a brief refresher, you might find the SitePoint Reference is enough to get you started again.
If you’re looking for something more in-depth, you’ll find a wide assortment of books and courses available at our sister site learnable.com/. There’s sure to be something there to suit you.
And, of course, you’ve already found a great community who will be willing to help you out if you get stuck. 
See at here: http://www.w3schools.com/
you can also write in google html tutorials or so and you will get a lot of help.
Well … yes and no. Don’t be fooled by the name, W3Schools is not in any way an official reference site, it’s just run by a couple of guys who have no link to W3C. It’s not bad, it presents a lot of the basics in an understandable way, but it’s not great either. It has mistakes on it, it has sections that are significantly out of date, and the authors don’t seem to have any interest in correcting or updating it. The links that TechnoBear gave are generally more reliable and will serve you better.