I tryed to install the hp photosmart c4340 all in one to my pc laptop.the installesion was incomplete.it can not be install as a usb printer.have changed the usb wire but have not fixed the problem.

Try installing the printer as a LPT Port or USB Port connection. Do not allow it search for any printers.
You can change port access later.
This is how I install my HP4050N Network printer.
ALSO, Is your network connection working properly?
Tihs

Many issues are caused when the HP Photosmart is connected to computer using a USB cable before the HP Photosmart software is installed on the computer. IF you connected the HP Photo smart to your computer before the software installation screen prompts you to do so, you must follow these steps.

Troubleshooting common setup issues :
1) Discoonect the USB cable from the computer.
2) Uninstall the software (if you have already installed it.)
3) Restart you computer.
4) Turn off the HP Photosmartm wait one minute then turn it on.
5) Reinstall the HP Photosmart software.

If your installation is incomplete, or if you connected the USB cable to the computer before prompted by the software installation screen, you might need to uninstall and reinstall the software. Do not simply delete the Hp Photosmart application files from your computer. Make sure to remove them properly using the uninstall utility provided when you installed the software that came with the HP Photosmart.

To uninstall from a Window computer and then reinstall
1) On the Windows taskbar, click Start, Settings, Control Panel (or just Control Panel).
2) Double-click Add/Remove Programs (or click Uninstall a program).
3) Select HP Photosmart Driver Software, and then click Change/ Remove.
Follow the onscreen instructions.
4) Disconnect the HP Photosmart from your computer.
5) Restart your computer.
Note : It is important to that you disconnect the HP Photosmart before restaring your computer. Do not connect the HP Photosmart to your computer untill after you have reinstalled the software.
6) Insert the HP Photosmart CD-ROM into your computer's CD-ROM drive and then start the Setup program,
7) Follow the onscreen instructions and the instructions provided in the Setup Guide that came with the HP Photosmart.

Was the printer new? Try it in another pc to make sure it's all right. Then try another usb cable. When you attach the cable, the pc should recognize when the printer is on.

Assuming this is a Photosmart 7550 printer and not the 7550 Plotter, this is what you will need for connectivity. To connect printer to PC, you will need a standard USB A/B cable... one side is a male A connector and the other one a male B connector. As far as the drivers are concerned, you will not need to download any. Vista already has a compatible driver for your HP Photosmart 7550. HP recommends selecting the drivers for the Deskjet 5550 when installing your Photosmart 7550.

Ensure the plug at the wall socket is on. Try a differenr USB port.

By new and barely used, do you also mean then, still under warranty? If so, return and exchange :-)

Sounds like an ink cartridge issue, though. Try swapping the cartridges out.

http://www.opendrivers.com/driver/282038/hp-photosmart-c4340-all-in-one-full-feature-software-driver-9.7.1-mac-os-x-v10.3.9-v10.4-v10.5-free-download.html

Try downloading the drivers from here
Just pick your operating system first
http://h20000.www2.hp.com/bizsupport/TechSupport/DriverDownload.jsp?prodNameId=3546237&lang=en&cc=us&prodTypeId=18972&prodSeriesId=3221641&taskId=135

A tip with hp printers is to NOT connect them until you have the software installed. so if you have it connected just unplug it run the drivers from the website and plug it in either when the installer tells you or when it has finished installing the drivers

All you need is a USB cable if it didn't come with one. One end will be shaped like the letter "d" and the other end will the flat. You will need a spare USB port to plug into.

after trying twice to down load,and the same code kept coming up.i decided to try one more time and for some reason it worked this time everything is now down loaded,