By "imaging it" he means, did you duplicate the contents of your old drive (ie, make an image your old drive) using backup software that mirrors the file structure of the old drive (ie, not just copy files from the old drive over to the new drive) and use said software to place the image on your new, larger drive?
I think the assumption is that this new larger drive is your boot drive (the one with the operating system on it)? If not, and you were just adding a larger storage drive, is the screen actually blank? Normally, if the bios is assigning the wrong boot device, you would end up at a black screen that says something like "non-system disk". To be sure, go into the bios (usually by holding the F1 or DEL key during the first few seconds of the boot sequence). Find the boot menu in the bios, and make sure the drive with your operating system is first on the list.
If you were trying to add a new boot drive, you are going to need to get the operating system on it. Either with an image of your old boot drive, or by reinstalling it (usually from either a bootable DVD or USB drive).
If neither of these things is the issue, then you may have, as others have said, dislodged something (usually either a power connection or memory dim, but could also be the CPU or video card). Because it was a drive, the first thing I would do is unplug and replug all the power connections going to your peripherals/drives. If the computer tries to start, and all you get is a black screen, with a couple of (diagnostic) beeps from the PC speaker, this is usually the problem. And in such a case you wouldn't be able to get into the bios normally.