When trying to print it says

HP LaserJets - Cold Reset Instructions Cold resetting a printer resets the printer to factory defaults.Please note: Any settings you make at the printers control panel will be reset to factory defaults, including the IP address if you have a JetDirect card installed. Remove the JetDirect card while you cold reset the printer if you don't want to erase the JetDirect card's settings.

You can also reset the NVRAM. Resetting the NVRAM will clear the page count and reset the service mode settings to factory defaults. On printers with a display panel you need to enter service mode to manually change the information stored in NVRAM. On printers that don't have a display panel, such as a 5P, 6P, 2100, 2200 there is a different procedure outlined below.

"Older" printers with a display panel. (e.g. 4000, 4100, 5si, 8000, etc.)

Cold resetting the printer is simply a matter of turning the power off, holding down the GO or Online button while turning the printer on.
Resetting NVRAM settings must be done manually through service mode. See entering service mode.
"Newer" printers with a display panel. (e.g. 2300, 2400, 4200, 4250/4350, 4300, etc.)

Turn the printer off and then on. When the printer begins its memory count, press and hold down the Checkmark button until all the main LED signal lights illuminate and stay illuminated. Then release the Checkmark button, and use the Up/Down arrow keys to find the Cold Reset option, then press the Checkmark button again to choose that option.
Printers with no display panel.
HP 1100, 1200 - While the printer is on, press and hold the Go button for 5 seconds. This will reset the printer.
To reset the NVRAM. Turn the printer off. Press and hold the Go button for 20 seconds while powering on the printer.
HP 2100 - To perform a cold reset, turn the printer power off, then press and hold the JOB CANCEL button. Turn the printer power back on and after all the LEDs come on release the JOB CANCEL button. A cold reset changes most system parameters in NVRAM to the factory defaults. The JOB CANCEL button must be released within 20 seconds after all of the LEDs come on; otherwise, an NVRAM initialization is performed instead of a cold reset.
HP 2200 -
Cold reset:
1. Turn the printer power off.
2. Press and hold GO.
3. Turn the printer power back on and continue to hold GO until the Attention light turns on.
4. Release GO.
5. The device lights will begin cycling from front to rear. The cold-reset process will run until completion and the device will go to the ready state.

NVRAM Reset:
1. Turn the printer power off.
2. Press and hold GO.
3. Turn the printer power back on and continue to hold GO until the Attention, Ready, and Go lights turn on.
4. Release GO.
5. The device lights will begin cycling from font to rear. The NVRAM initialization will run until completion and the device will go to the ready state.
HP 5P & 6P
Cold reset:
Turn the power off and hold the reset button (button closest to the back of the printer) for LESS than 20 seconds while turning the printer on.
Reset the NVRAM:
Turn the power off and hold the reset button for MORE than 20 seconds while turning the printer on..

To clear the memory:
Press the ENTER/MENU button one time.
Press the < or > button until Fax Functions appears in the control panel of the printer.
Press the ENTER/MENU button one time.
Press the < or > button until Clear Memory appears in the control panel.
Press the ENTER/MENU button one time to clear the memory.
The HP LaserJet 3015 comes with 32MB of memory, enough to hold about 250 monochrome pictures.
Possibly also you are trying to print too large a document, try clearing all documents and then try printing using a different format or program. I have found that some HP when trying to use windows picture viewer to print will give a memory full error, but the same doc printed from windows paint or inserted into word will print fine. The difference is that some programs spool the print job so it prints in sections using windows memory instead of trying to load the entire doc or pic into the printer memory.