To whom

[Zee10]

To whom you want to speak with?
Whom you want to speak with?

I am the first to whom this responsibility has been given.

Which compnay are you calling from?

Which item do you want to buy? Or which item you want to buy?

Please advise if above are correct.

[GoesStation]

To whom you want to speak with?
Whom you want to speak with? (The sentence doesn't have a main verb.)

I am the first to whom this responsibility has been given. (This sentence is grammatically correct but not natural. Write I am the first to be given this responsibility.)

Which company compnay are you calling from?

Which item do you want to buy?
Or which item you want to buy?

Please advise if the above are correct.

See notes above. If you want to construct a proper question, start by writing it as a statement. For example, You want to speak with X. Now move x to the beginning and replace it with "Who do" and you get Who do you want to speak with? Your teachers may tell you to write whom​. This is rarely done by native Anglophones.

[Zee10]

Thanks.

I always get confused with "a" and "the", because i don't know where should i put them.
Please advise.

The file is getting opened. Is it correct?

[emsr2d2]

Thanks.

I always get confused with "a" and "the", because I don't know where should I should put them.
Please advise.

The file is getting opened. Is it correct? Please ask this unrelated question in a new thread.

In your post, you need "the above" because it's a shortened form of "the sentences which are above". I'm sure you know that you need "the" before "sentences" in that construction.

Note my correction to your word order above. You used "should I" instead of "I should". "Should I" would be correct within a question, for example "Where should I put them?" Your sentence was not a question because it started with "I don't know ...". Because it's not a question, the normal "subject + verb" word order is used.

Remember to capitalise the word "I" every time you write it.

[Zee10]

Thank you.

As you explained to me, I was not supposed to write "shoud I" when sentence starts with "I dont know" etc.
I understood your point.

Regarding same type of sentences, I have another quotation below.

When sentence starts with "please advise" then what should I write?

Which are correct below?
Please advise when will you deliver the material?
Please advise when you will deliver the material?
Please advise when can i expect your order?

[GoesStation]

Sentence 2 would be correct if it ended with a period ("full stop" in British English).

Sentences that begin "Please advise" are statements, not questions, so you can't invert the subject and verb. Therefore sentences 1 and 3 are incorrect with or without a concluding period.

[Zee10]

If sentence 2 is correct then shoud I put question mark at the end?

You wrote, if it ended with period.
Should not it be "It is ended" passive voice or in active voice " it ends with".?

[GoesStation]

Sentence 2 is incorrect with a question mark. It would be correct with a period.

In other words, if it ended with a period, it would be correct. That is a conditional sentence, not the passive voice.