*There is nothing for me to answer
*There is nothing for me to say [in response]
*There is nothing for me to respond with

Concerning the inevitable difference in the exact English version:
English's interpretation of the same ideas manifests differently, primarily in the fact that the word "respond", or the word "answer" (as a verb), can not seamlessly be used, though they are the most accurate translations of ответить. The English versions given above... Lack grace. Instead the best way to translate for a book or something important would be "I have no answer", or just utterly changing the sentence. Russian can use ответить whenever it fits in meaning, but each language at any given moment must also act according to its respective syntactical restrictions and patterns. Russian, being awesome, not only exhibits more ~possible~ syntactic structures for expression, but also manages to keep them all organized and non conflicting with one another. So both the нечего, некуда, некогда etc. constructions meld seamlessly with the completely unrelated "кому-либо + (infinitive)".

Another example of English shortcomings in this area would be the fact that you can't put a preposition before the relative pronoun "that". Any prepositions that ought to, get put at the end. A shame.

The bottom line here on my off topic rant is:

Кому-либо (не____) (infinitive). - not only gets translated in varying ways do to English's lack of an exact way to express the same "mood" (which in and of itself may not necessarily be a damning flaw), but any English translation for the construction will be NON-universal, and flawed.

Obviously English still works as a language and all/ none of this matters all that much; it's just flaws of grace like this that make me dislike the language.