"sda1" would be the first partition on the first hard drive (if there is more than one HDD) in the computer. The physical drive itself would be referred to as "sda." The second physical drive would be "sdb" and so on.
If the hard drive has indeed gone bad, you power off the computer, take off the case, remove the old one and put in a new one. The new one will need to be formatted, partitioned, and have an OS installed to it.
If the HDD does look like it's going bad, the absolutely first thing you must do before additional troubleshooting is back up any crucial irreplacable data files to external media, either a removable drive, disks, or across the network to another computer. Then, once you are running, work up a back up strategy (even if it's just "back everything important up once a week) and stick to it. BTDT, only in my case, it was stolen laptop that opened my eyes.
With some laptops, changing HDDs is easier than others. There are many videos on YouTube showing how to do this.
Last edited by frankbell; 09-18-2011 at 08:46 PM.