Maybe she changed her phone number. People do that all the time here....and maybe you got the address wrong.
Here's just one of thousands of entries for that name. :-
Helen Barnes - Newcastle Upon Tyne NE6 - full address - 192.com
www.192.com › AZ-People
We have a record for a Helen Barnes living at an address in Newcastle Upon Tyne NE6. The record includes the full address, along with information about the source of the data that will show whether the address is likely to be current. 192.com has records on millions of UK people and addresses.