Before looking at those two options, check the obvious things first - ie, check the hard disk is actually connected (once in a blue moon, they can sometimes work themselves loose depending on the design of the machine) - if it's easy to get to, remove and reseat it to make sure. Listen carefully when you turn the machine on - does it make any clicking or whirring sounds (not the fans, and remove any CD from the CD drive)?

Is it an Amilo Pro or a Lifebook?

If it still refuses to play ball, then consider a new hard disk - about £40. No point binning a perfectly serviceable laptop.

PS...you have a backup of your data don't you?