We'd be completely fucked without the internet. Online banking for a start, card payments would all stop. We'd all have to go back to cash. But all the branches have shut down, post offices, and most of the cash points gone.
There would be no Netflix, Disney +, Iplayer or any other streaming/catch up service. All the mobile phone networks would cease to function, not even for voice calls or SMS.
Almost everything would grind to a halt, all the shipping and distribution services reliant on the internet. Supermarket shelves would be empty, and it'd take months to get things moving again.
Imagine all the stuff that's moved online having to go back to old fashioned paper and pen, it's almost unthinkable.
Every app, and smart device would stop working - from your ring doorbell, heating system to your car app.
If the internet disappeared tomorrow, we'd be completely fucked since we're absolutely dependent upon it for almost everything. It'd wouldn't be just like rewinding 30 years, we'd almost be back to the 1800's, and it'd take ages to come up with offline alternatives. Landlines are gone, fax machines gone, all that pre internet tech has been chucked in a skip.
Basically the internet is all out eggs in one basket, and whilst the whole point of it is that it was designed to be resilient, when AI goes rogue and decides it wants to wipe us out, the first thing it will do is take over every router on the internet and shut the whole network down in a way that's never been seen before. It won't be quaint, it won't be a bit inconvenient, it'll be eating spam by candle light for the next 3 years bad.