I have two flights. From Seoul to Delhi and from Delhi to Afghanistan, with two different airlines and two tickets. At Delhi I have to take my baggage by myself and transfer it to my second Delhi-Afghanistan flight. In this case I need to have a transit visa to pass the passport control and to get my luggage. So I am not entering India but just want to take my luggage. Can I get the transit visa exactly in the day which I arrive at Delhi international airport ? or must I get the visa before my travel ?
You'll need to get a visa before you travel. On arrival visa is not available for citizens of Afghanistan.
The "on arrival" visa has been replaced with the online e-visa. The countries whose citizens are eligible to apply for an online visa is available on the official website.
If your country of citizenship is not listed there, then you need to apply for a regular visa from the Indian embassy.