My lexmark e250d had an error asking for a new photoconductor. I replaced this part and the display returned to normal with the single blue light but it will not print anything now. Its like the lights are on but nobody is home I replaced the toner cartridge and photoconductor.

Here is an excerpt I found from the W840 user manual. Looks like you need to change the photoconductor kit. Here is the link for the user manual: images.lexmark.com/publications/pdfs/w840/eng/ug.pdf
To ensure print quality and to avoid damage to the printer, the printer stops operating after the photoconductor kit has reached approximately 60,000 pages (Letter/A4). The message 84 Replace PC Unit is displayed when the printer reaches this point. If the Toner Alarm setting is set to Single or Continuous (default is Off), the printer automatically notifies you before the photoconductor reaches this point and displays the message 84 PC Unit Life Warning. To avoid having the printer stop operating, replace the photoconductor kit when you first receive the 84 PC Unit Life Warning message. Once the photoconductor kit has been replaced, normal printer operation resumes

Define "won't print".
Does your computer show the printer as attached, and "online" or "offline" ?
When you try to print a "test" page, do you get an error-message? Exactly what?

84 PC Life Exhausted indicates that the photoconductor unit has reached its functional life. The photoconductor kit will need to be replaced. The printer will not function so long as the Exhausted message remains on the display. The only way to clear the message is to install a new photoconductor. After replacing the photoconductor unit, you need to manually reset the pc page counter as well. Thank you for choosing Lexmark.

Here's an article on How to Change the Photoconductor Unit/Kit on a Lexmark E250d(n), E350d, E352dn, or E450dn Printer. Just click on this link: http://bit.ly/aykTXL. This should give you an idea on how to install the photoconductor unit in the Lexmark E352dn printer.

NOTE: If you are replacing your old photoconductor unit with a new one, after installing it you will need to reset the photoconductor counter as well.

If you are using a Lexmark factory new or Lexmark reconditioned PC I suggest you contact Lexmark Technical Support via the Lexmark website www.lexmark.com or call the Lexmark Technical Support number.

If you purchased a genuine Lexmark part, it is under a warranty. Make sure you have your purchase receipt handy for purchase verification.

If not, you are limited to your point of purchase for additional assistance.

Don

Instruction sheet photoconductor kit for Lexmark E250D on this page:

http://support.lexmark.com/index?page=content&segment=DOWNLOAD&locale=en&userlocale=EN_UK&id=HO2997&productCode=LEXMARK_E250D&actp=TOP_DOCS

Go to www.lexmark.com Select the correct country. then Selectg "Technial Support" Enter the model of your printer "E350D" Click on search. Under the "Knowledge base" header place this number into the search bar: "ENUS27198" click on search. ************************* Lexmark E350d Country / Region: United States Language: English Need to download a driver? How to Reset the Photoconductor Page Count on a Lexmark E350d or 352dn Printer ID: ENUS27198 Procedure Follow the steps in the table below to reset the photoconductor (PC) page count. NOTE: The directions in this article are in English. To download a PDF file containing these instructions in several other languages, click here (file size: 782 KB). Step Action 1 Enter the printer's Configuration menu: Power off the printer. On the printer's operator panel, press and hold the select button () and the back button (). Power the printer back on while keeping both these buttons held down. When you see the messages Performing Self Test or Busy on the printer screen, you can release both buttons. If the printer has successfully entered configuration mode, you will see a new menu with the heading CONFIG MENU at the top of the screen. 2 Press the right arrow button () until you see Reset PC Cnt. Press once. You will see Reset. Press again. The printer will display a Resetting PC Count Value message and go back to the previous screen. 3 Press once. 4 Press or on the operator panel until you see Exit Config Menu. Press once. Selecting this will cause the printer to reboot. If the counter has been reset correctly, the printer should return to a Ready prompt. 5 If this does not clear the PC Life Warning or Replace Photoconductor message, power off the printer and attempt this entire procedure again. If the error remains after two attempts, confirm that: The correct photoconductor unit is installed. The part number on the photoconductor unit should be E250X22G. If it is not, install the correct photoconductor unit into the printer. The photoconductor unit has not been refurbished by a third party or is not damaged in any way. If the photoconductor unit was refurbished by a third party or appears to be damaged, try replacing it again before seeking service on the printer. If the error persists, the printer may require service to correct the issue. Contact Lexmark Technical Support for more information. Don

Here is how to reset the photoconductor kit counter:

1. Make sure the new kit is installed and the printer is turned ON.

2. Open the front panel.

3. Hold the Cancel button in until the front panel LEDs flash.

4. Close the front panel

Here is how to reset the photoconductor kit counter:

1. Make sure the new kit is installed and the printer is turned ON.

2. Open the front panel.

3. Hold the Cancel button in until the front panel LEDs flash.

4. Close the front panel

According to Lexmark E450DN service manual;
1. Turn off the printer.
2. Press and hold Checkmark and Right Arrow buttons.
3. Turn on the printer.
4. Release the buttons when 'Performing Self Test' displays.
The message CONFIG MENU displays on top line of operator panel.
5. Scroll down and select 'Reset PC Cnt.'