Questions & Answers about Я простудился и не пойду на работу.
Why is простудился used here instead of an imperfective verb?
Простудился is the past tense of the perfective verb простудиться (to catch a cold). It is used here because the action is completed and has a direct result on the present situation: you are currently sick, which is why you are not going to work.
What is the purpose of the -ся ending on простудился?
The suffix -ся makes the verb reflexive. While English just says caught a cold, the Russian verb простудиться acts a bit like to chill oneself. Many verbs describing changes in your own physical state or illness take this reflexive ending.
Why use the perfective verb пойду rather than a form of идти?
Пойду is the future tense of the perfective verb пойти. It is used because you are talking about a single, specific planned action in the future. If you used the imperfective иду, it would mean you are in the middle of walking there right now.
Why does to work translate to на работу instead of в работу?
The noun работа is a special word that always takes the preposition на instead of в for locations and destinations. Because you are talking about a destination (motion towards it), you use the accusative case, changing the ending from -а to -у.