Myths are a classic source of inspiration, and taking an old myth and modernizing it is an often used trick of authors to tell a story. Ulysses, for example, by James Joyce (and touted as the greatest novel of the previous century), is based off of the Odyssey.
So take a myth and mix it up a little. Put it in modern day, change the characters a little bit, and see what happens. Don’t limit yourself, either – the Greeks and the Romans had some great myths, sure, but there are other cultures out there that have some weird ones.