My Cat Is Scratching Everything

[Gabby]

hi,

I have a cat for the last 12 months - I got her as a kitten and she has been grand. In the last 4 weeks or so however, she is scratching everything in sight! My leather couch is destroyed, the wood floors and even the walls in some rooms. She doesn't seem to be scratching herself - it is just other items around the house. Can anyone shed any light into what is happening? Could she be pregnent?
As you can probably telll, I don't know much about cats but she has been no trouble up until now.
Help!!!