I'm not entirely sure as there could be many 'solo leve light novels'. Generally, a light novel might be about various things like a solo adventure of a character, perhaps their journey of self - discovery in a fictional world. It could involve magic, battles, and relationships in a relatively easy - to - read and often youth - oriented style.
You can start from the chapter where the anime ended. Usually, there are online forums or manga communities that can give you the exact chapter number.