If you've not done so already, try toggling flight mode to ensure your phone hasn't "dropped off" available coverage.
Use the "check service status" option on https://ee.co.uk/help/mobile-coverage-checker in the first instance, to check for local service outages. A loss of coverage will remove the ability to make/receive calls, send/receive texts or use mobile data.
If you're in the UK and have a WiFi connection, you can use WiFi-calling to keep using your phone as normal without needing network coverage. Home broadband uses different technology, and will be an unrelated issue - unless that's also with EE and there's an account issue.
