I fell down my notebook and now i need boot disk. what should i do ?

The time bar may be telling you that there's damage to the hard drive, or perhaps just your hard drive's main partition.
If your Mac is running OS X Lion or Mountain Lion, you should have a recovery partition with Disk Utility on it. Restart your Mac while holding down Command-R to boot into this instead of your regular partition. Follow Apple's instructions on how to use Disk Utility to see whether the hard drive is damaged or just corrupted (and potentially corrupted).

First try a system restore/recovery. Scroll down to System recovery : http://h20000.www2.hp.com/bizsupport/TechSupport/SupportTaskIndex.jsp?lang=en&cc=us&taskId=110&prodTypeId=321957&prodSeriesId=3744231. If that fails, remove HDD and test, replace if necessary.

Hold down the power button until it turns off..

Most likely in this case, the damage is to the hard drive or its connection to the motherboard. The CQ series though has a three point screw attachment for the hard drive so Im more inclined to think that the shock of the landing has damaged the read/write head on the hard drive. If you happen to have another hard drive for a laptop, try installing a new drive and run the installation disc and see if it will complete and boot completely....if it will then the problem was the old drive.

That usually means you do not have a valid system to boot from. The disk may be good or bad, can't tell, yet.
The best would be to go to an Apple store and ask them. It's worth a 200 mile drive. Also visit http://discussions.apple.com/category.jspa?categoryID=218 Apple - Support - Discussions - MacBook.
Get your CD/DVD-ROM boot disk that came with the computer or with a newer OS and start up from that--hold C down on startup as you insert the disk. Then after the language choice select from the menus, not the screen, to run Disk Utility. Pick out your drive and Repair Disk. Follow that by Repair Disk Permissions. It should be saying Write Status : Read/Write, S.M.A.R.T. Status : Verified, Partition Map Scheme : GUID Partition Table If both of those work, then you should be able to browse your disk and you should be able to reboot. If troubles, you may need to use Target Disk Mode (reboot holding the T key) and access by Firewire or for 10.5 or later by USB from another Mac. -Ken

Sorry, but if your hard disk fell down and now isn't regognized by the computer the most possible situation is that the disk is destroyed.

Stelios.

try reset bios to defaults.

Usually, your computer tries to "boot" from multiple sources:

1. 3.5" diskette drive, if installed, functional, and a boot-diskette is inserted
2. CD-ROM drive, if installed, functional, and a boot-CD (such as the Windows XP CD-ROM) is inserted
3. disk-drive, if installed, functional, and the "boot" record can be read from the disk-drive
4. from the Ethernet network, via a "networked boot server"

So, "check cable" means that either no Ethernet cable is connected to the computer, or that the "networked boot server" is not installed, or the boot-server did not reply.

What this means is that your disk-drive was damaged by the fall, and the "boot" information cannot be read from the disk-drive.

So, you need to replace the disk-drive.

This usually means a corrupted disk structure. From your latest install disk, even the original, put in the CD/DVD and power up holding the C key down until it loads the installer. Answer the language question. From the Menu Bar, select Utilities or Disk Utility. In there select your drive on the left and then press Repair Disk. After no errors, press Fix Permissions. There may be some "errors" shown for permissions that can be ignored, they have used links (lrw...) where it expects none. This will most often fix the problem.
You might try a "safe mode" boot, since System 6 or before. Hold the shift key down while booting. You will not have networking or drivers for mice, etc. You may be able to Repair Disk and get things working this way. Holding the Option key down allow you to select another disk if you have bootable system on it, USB or Firewire.
There seem to be a lot of this problem lately. Just remember to Verify/Repair Disk and Fix Permissions before and after every install. -Ken

remove all disks try booting agin disks may have infection
check bios/cmos make sure ur hdd is detected
if still no try reloading/repairing windows from disk