The word 'not' makes the verb negative.
The word 'no' makes the noun (lyrics, reason) negative. 'No' is a kind of determiner (like 'any' or 'some') - it isn't like 'no' in a negative sentence in Spanish.
You need to bear in mind two differences between Spanish grammar and English grammar:
- In English, the word 'no' cannot make a verb negative.
- We only usually have one negative word in a sentence.
In the sentences in your examples, there are two ways of expressing the same idea:
1. You can have a negative verb with a positive noun:
[There isn't] [any reason to do it]
[There aren't] [any lyrics for this song].
2. Alternatively, you can have a positive verb with a negative noun:
[There is ] [no reason to do it]
[There are] [no lyrics for this song].
I've used brackets [ ] so that you can see that the word 'not' belongs with the verb, while the word 'no' belongs with the noun.
Similar sentences are "I have no money" (where "no money") is the object, or "I don't have any money" (where "any money" is the object).
I hope that all makes sense.