What happens if everyone disconnected from the blockchain
Computers are not connected to the blockchain.
Computers running Bitcoin software connect to a few other computers that are running Bitcoin software.
Each of these computers keeps its own copy of the blockchain if they are what is known as a full-node. For example any computer running the &quot;Bitcoin core&quot; wallet software is a full node. So even if they don't communicate, this blockchain data is not lost. The old transaction data is still stored on many thousands of computers.

No node ever needs to trust any other. Each node that has a copy of the blockchain can use it to check that new blocks are correct.