The hard drive has failed.  Replace it - any 2.5" 9.5 mm SATA notebook drive will work.

See if anything here applies: MS Article   You should run the Dell Diagnostics including the extended hard drive test.

Ok, so I replace hard drive; is there a way to get the stuff off old HD and on to new? Worried about getting Windows and all loaded. Is there a way to access the restore file that is on computer, we didn't get actual disks to restore with is all on computer. Thanks so much for all help

If you need to recover data, purchase a 2.5" SATA USB 2.0 drive case (newegg.com has dozens of these). Mount the drive in it, and attach it to a working system by USB.  Copy your data.

Copying and restoring the Dell recovery file isn't easy.  Better would be a clean install.  If you're in the US, you can order a Windows CD/DVD free of charge;  see below.  Outside the US, contact your local Dell office.

http://support.dell.com/support/topics/global.aspx/support/dellcare/en/backupcd_form?c=us&l=en&s=gen&redirect=1

Will this one work with Vista on my Dell Inspiron 1525? Let me know if you know of a better HD in that price range.

http://www.newegg.com/Product/Product.aspx?Item=N82E16822148375&nm_mc=OTC-C173T&cm_mmc=OTC-C173T-_-Hard+Drives+-+Notebooks+/+Laptops-_-Seagate-_-22148375

Yes, that will work just fine.

I have had  the same problem with my inspiron 1521. I have purchased a hard drive enclosure and removed the hard drive from laptop but when I have connected it to my sons laptop the hard drive size is only 9.99 GB . The laptop came with 2 hard drives but I had imagined there were not actually 2 physical drives but that they had been compartmented or something ( apologies for knowing very little about putas ) Where will I find the other hard drive so I can try and retrieve my data as it is the other larger drive where all my personal files and stuff is on.

Thanks Loz

Sounds like the main partition on the drive is history - if you need the data, contact Drive Savers, Ontrack, etc. - they can work miracles but expect a bill of a couple of thousand dollars for the recovery.

Yes.  You'll also need to take ownership of the files before you can copy them:

http://www.tipandtrick.net/2008/how-to-take-ownership-and-full-control-permissions-of-files-and-folders-in-vista/

After running the full disk scan and selecting auto repair etc I can now see the 220 GB hard drive phew ! do I just make a folder on sons laptop and copy and paste from the old drive ?

thanks again Loz