I think it is unlikely that your old lens damaged the camera. The electrical contacts are in a block at the top of the lens mount – It would take a pretty hard hit to damage those. If the contacts in the camera do not look damaged then they are very like okay. Depending on how long you have had the camera it could be a good idea to clean them.
Has your friends lens every worked properly on your camera?
You say it does not achieve focus – does this mean that it continually hunts? or are the images just always OOF? or does it not even try to focus?
It may help if you can post a sample image with EXIF data intact.