I'm not a hardware expert by any stretch of imagination, but I thought I could handle a simple exchange of hard drives easily enough. Apparenlty, I was wrong. I took out the HD from my old Vaio laptop (working) to put into a friend's Dell laptop (not working, bad HD). I switched them very carefully, connected everything just the way it was and – nothing. I googled around a little and found out that I had to "set the jumpers" the way they were before the switch, but I don't know what that means? Could someone help me out here?
Jumpers are little pin connectors in the back of your hard drive. Their position signifies whether the drive is set as a master (MA), slave (SL), cable select (CS), or something else. You need to change their position so that they match the positioning they had on the previous drive (the malfunctioning one that you took out). I hope that clears things up for you.