Answer
The answer is German. Manna Dey, the legendary Indian playback singer, had a prolific career spanning over five decades, during which he recorded songs in numerous languages. His repertoire covered a vast array of Indian languages such as Hindi, Bengali, Marathi, and Kannada, as well as international languages like English and French. Notably, German is one of the few languages in which Manna Dey did not record any songs.