That's certainly one possibility. Or it might be a BIOS setting that's been reset so your PC just can't see the hard disk any more, or is trying to boot from another device first - like a floppy or a CD that isn't there.
Just because your PC can't boot from your hard disk doesn't mean the disk is bust. Might just be the operating system that's missing a file or two - or a registry setting that's got changed somehow. If you can take the disk out and try it in another machine you might be able to read your data from it even tho it won't boot.
A hard disk on its own is around £25-30 upwards depending on size/speed etc. and fitting one is easy enough. The hard part is that you have to re-install Windows (or whatever OS you're using), and all your apps, and somehow put your data back together again from backups. Retrieving data from broken hard disk is often possible but usually expensive.