RE: Hard Drive Failed during diagnostic. Error Code 2000-0142
The drive needs to be replaced. If the system is under warranty, call Dell with the error and they'll arrange that.
if the system is out of warranty, and you need a recommendation for a replacement drive and installation instructions, we'll need the full model number (i.e., Inspiron N5110, 5521, etc.).
You're also going to need a set of recovery media -- if you did not prepare one when you received the system, you'll either need to download and make that (newer systems) or call Dell to purchase it (older systems).