I'm guessing that you new provider supplied you with a new router, which has got a different wifi password to your old one. With modern routers and printers the chances are that they both support 'WPS', meaning that you only need to press a button on each of them. However you probably need to go via a menu to find the 'WPS' option on your printer, so we need to know which model you've got in order to provide instructions. (It might also help to know the make & model of your router).