Can anybody answer these at least as much you know?

The difference between or when we should use these words
“A” and “The”
“FOR” and “TO”
“Go” and “goes”
Told, speak and said
Then and Than or Then only and Than only
Made and make
That or Which
When do we use these words “DO” “AS” is used
Has and does?
May be and Might be
Could would and should
All though and even though
To the office OR for the office which one is the correct?

Is there any rules to use or when should we must use these words
IN, ON, ACROSS, FOR, TO, AROUND, ABOUT, OF, BY AND OVER: overthere but not that completed: over)
Please reply to rajeshhenjarappa@yahoo.co.in
I will be waiting for your reply bye

What are you awaiting? The usage of these words is basic knowledge.
I'll try to explain about that:

a boy (you don't know the boy) <-> the boy (sb. you've already mentioned)

"for" and "to" have too many meanings. I can't explain you all of them.

I go, you go, he/she/it GOES, we go, you go, they go

to tell a story (sb. listens while you're e.g. reading sth to him/her)
to speak with sb. (you're having a conversation with sb.)
and than I said... (to say a word, for example)

then I saw her coming (you saw her at this moment)
I'm thinner than ever (you've never been thinner before)

I make fire (you do it now) <-> I made fire (you did it in the past)

That is beautiful
I saw a cat, which was beautiful

"do" and "as" have downright different meanings

she has a cat (she owns a cat)<-> I do my homework (I prepare it)

May I help you (you ask if you're allowed to help) !OR!
I'll may see you(you're not sure)<->I'll might see you(you're rather sure)

could it be that...(is it possible that...)
I would love to see my girlfriend (I don't have the possibility yet, but would see her if I could *g*)
you should/ought to do your homework (you're supposed to do it)

Although <-> even though <-> albeit <->...no difference

I go to my office every morning
I prepare a deed for the office (do you see the difference in meaning?)

IN, ON, ACROSS, FOR, TO, AROUND, ABOUT, OF, BY AND OVER....sorry but you have to learn the usage of these words on your own. Often, they are used at random. This needs to be learned.