Not really enough details to diagnosis the problem, so I will make a couple assumptions and suggestions based on them....
I am going to assume that the hard drive is good, but something is preventing the computer to complete it POST (a small utility it uses to check the memory, etc, and then load the hard drive). If the POST is failing, you will not get the manufacturer's logo or any kind of an error.
The most common cause of this is either loose memory or a lose card. As it sounds like the PC was moved just before the error began, odds are that either a memory chip or an add on card was knocked loose. If you are comfortable opening the computer. with the power off make sure the memory is properly seated and any cards are in tight. If you are uncomfortable doing that, ask one of your favorite "geeks" to help you. 10-15 minutes project. (Going price is a McDonald's meal or a video rental.)
If you are unable to get the computer to boot, you can recover the data by having a "geek" help you remove the hard drive and place it as a scone drive in another computer. They will be able to see the drive and copy off anything you need to CD or DVD. They can also do the same thing using an enclosure or adapter as listing by the first two postings.
If you take the computer into a shop, be aware that the most common way to fix ANY problem is to wipe the drive and reinstall Windows. If you take it in, have them put in writing that they will NOT wipe the hard drive without your permission.