|Perhaps clarify - are both the router and isp new - or just the isp?|
Your info does seem to imply only the isp has changed, that the router is as before?
If only the isp then you need to reconfigure your router to use the new isp account. The info required for that will be provided by (or ought to have been provided) by your new isp.
That info will be your user-name and password for the new isp account.
You can only do this by accessing the router setup via a cat-5/ethernet connection; it cannot be done over wifi.
Until you reconfigure the (your former) router with user-name/password from your "new" isp - you will not be able to use the router to get online; be it via wifi or cat-5/ethernet...
The make and model of your router will be useful here as it will enable pholks to guide you more specifically how to go about configuring your original router afresh with/for the your "new" isp.
If you have a new isp "and" a new router (from your "new" isp presumably) - then post back.
Typically, isp provided routers are already setup to be used out of the box. - but wifi may "not" always be enabled by default. Even if wifi is actually enabled (rare in my limited experience) you will need to know both the SSID (the router's name it broadcasts over wifi) "and" the access key. "Both" are often on a sticker on the base of a typical router (as supplied by most isp); and often included within the box on a card or in the instruction manual). If this is the case here - when you latch onto the correct SSID, you enter the access-key as given on the "new" router's base sticker, and/or included with it in the box as delivered.
So which scenario do you have? The same router but a "new" isp; or both a "new" router and a "new" isp?