My 2003 laser jet 1320 suddenly quit printing.

Do you have the 1320D or just a 1320. Only the D version will duplex automatically. The base version requires you to manually duplex. If you are sure you have the duplex version, then check the settings in the print driver and make sure it shows that the duplex option is installed. The driver often defaults to no duplexer.

To reverse an image for iron-on transfers
1. On the File menu in your software application, click Print.
2. Make sure the product is the selected printer.
3. Click the button that opens the Properties dialog box.
Depending on your software application, this button might be called Properties,
Options, Printer Setup, Printer, or Preferences.
4. Click the Features tab.
5. In the Paper Type drop-down list, click More, and then select HP Iron-on Transfer
from the list.
6. If the selected size is not what you want, click an appropriate size in the Size list.
7. Click the Advanced tab.
8. In the Features area, select the Mirror Image checkbox.
9. Click OK, and then click Print or OK in the Print dialog box.
For support call Our Toll-Free 1 888 224 4280

Install a new fuser.

Try unplugging the power cord and plugging it back in. Check to make sure that there are no paper jams or foreign objects stuck in the rollers. Reseat the toner and make sure the lid is firmly closed.

If ink is ok , then you may need to reinstall printer drivers.

Unplug printer USB.
Go to control panel>>Installed printers and delete existing printer installation.
Reinstall printer driver software using printer CD.

GO TO PRINTER MENU AND CHECK THE JOB IN QUE AND CHANGE FROM OFFLINE IT TURNS TO READY

I have had a similar issue with both laserjet 3005N and 1320N machines setup as network printers on a windows 2003 print server. Both machines install correctly and print test pages but once you push to much of a print job to it (in my case it was a 12mb pdf file) the printer stops printing and never prints again for some reason. After a quick reboot a test page will print but what gives?? Buffer issues? Not enough ram? None of this makes sense since the printer displays nothing and just stops printNo test pages or anything. I tried re-installing it and rebooting it. Nothing.

Sounds like a corrupted print driver. Try removing/deleting your current print driver and re-installing a new updated one. Here's a link for the new driver:

http://h20180.www2.hp.com/apps/Lookup?h_lang=en&h_cc=us&cc=us&h_page=hpcom&lang=en&h_client=S-A-R163-1&h_pagetype=s-002&h_query=LaserJet+1320&submit.x=4&submit.y=4

Hope that helps you.

I want the software of laser jet 1320 printer

have you try to replace the toner ?

could be that or your fuser or dust in the laser assembly.