When we want to introduce reasons for our actions or state etc we use because and because of.
They are used to answer why something happened or is happening or will happen. But there is a little difference between because and because of in their usage.
Because: Because is conjunction followed by a clause (sub+verb)
•The guests went away because the function was over.
•Sabila broke up with her husband because he was a hypocrite and dishonest man.
•He couldn’t attend the meeting Because he got faint suddenly.
Because of: Because of is a preposition followed by a verb + ing or a noun.
•Because of his illness, he didn’t attend the meeting
•Because of her stupidity, he canceled the deal.