A S.M.A.R.T. test failure indicates that the hard drive is in a critical state. The most common error is that users fail to act immediately to back up all important data including: pictures, documents and any other files that need to be preserved. Backing up the hard drive should be done immediately. It is possible that some data has already been corrupted or completely lost. Once the hard drive has been backed up, it can be replaced.
The Dell Inspiron E1705 is a similar computer and the hard drive replacement
walk through can be used to replace the hard drive in the Dell Inspiron 9300. [guide|3990]