help??

Anyone ever go from being in a relationship and 2-3 weeks later their ex contacts them? how do you go about the situation, ignore them or respond? also did you ever contact them first? he was with some females the first week, it’s been 2 weeks since he’s posted anything and nothing. he tried contacting me but I ignored him, just debating if I should contact him or give it a few days to see if he tries again. I know this sounds super stupid. we dated 2 years.