You can reset the print head in the following ways:

Lift the scanner cover. You can do so by lifting the plastic tabs that are present on both the sides into a position when it securely locks itself in the locked open position.
Check the position of the print head. If it is on the left side or at the center, then it is at rest. But if you find it on the right side, then it means it is still under the process. To stop the receiving of the commands. Press the stop button for a while. As a sign, the print head will come to the center when it will stop the process.
Now unplug the printer from wall outlet.
Gently move the print head with the tips of your fingers.
Examine the area carefully to see if there are any bits of paper in the area and remove them with the help of tweezers.
Lift the scanner to release the lock and push it back in to close it.
Solution 2:

Firstly, ensure the power cord is directly connected to the wall outlet.
Now disconnect the power cord while your printer is still on. You can find the cord at the back of the printer.
Please remove the power cord from the wall outlet.
Remove any USB cables if they are connected.
Now wait for two to three minutes. Hold the power button for thirty seconds to remove any charge left.
Plug in the power cord back into the wall outlet.
Ensure the power cord is directly connected to wall outlet. This is important for the process as it needs a direct supply of power into your HP printer.
Reconnect the other end of the power cord to the back of your HP printer.
The printer automatically get switched on.
Solution 3 to change & reinstall the toner cartridge:

Keep your printer switched on for ten minutes so that the internal fan can cool down the extremely hot parts inside your HP Printer.
Open the front cover.
Safely remove the drum unit and toner cartridge assembly.
Unlock the lever and take out the toner cartridge.
Take your new toner cartridge in your hands and shake it from side to side to evenly spread the toner inside the cartridge.
Remove the protective cover.
Now fit the new toner cartridge into the drum unit. When you install the toner cartridge properly, you will see the lever automatically getting lifted.

THE ERROR CODE PROBLEM OF MOTOR POWER SUPPLY BOARD (SMALL DAUGHTER BOARD TOP OF THE SCANNER UNIT), Transistor no of 905,903 like ..before you change check motor is short ….or good..then fix that,  it will work..

Please reset the printer

1. Turn off your printer
2. Press and hold the STOP/RESET button
3. Press and hold Power ON button
4. While holding the Power ON button, release the STOP/RESET button
5. While holding still the Power ON button, press twice the STOP/RESET button
6. Release the Power ON button
7. Wait until it display an “idle” message. It will take about a minute.
8. When “idle” appear, open the top cover to expose the cartridges.
9. Lift up the cover for cartridge holder and take out both the black and color cartridges
10. Return the cover of cartridge holder and turn off the printer
11. Return the top cover and turn on the printer again
12. After the printer initialize, return the cartridges.

1. Go To Control Panel
2.  Go To Administrator Tools->Services
3. Find Function Discovery Provider Host->Startup Type->Automatic (delayed start)
4. Find Function Discovery Resource Publication->Startup Type->Automatic (delayed start)

1. You have an anti-virus software preventing the installer from launching. Disable your anti-virus software and run the installer again.
2. The installer is being blocked by Windows Vista. You can unblock it by right-clicking the installer and going to “Properties > General > Advanced” and select the “Unblock” option.

Fusing Unit Third Jam Error (Fatal Error)

Causes

The exit sensor failed to detect the leading edge of the paper within the prescribed time and triggered a jam alert.

Make sure the fusing unit has been installed correctly

Print Unable 71 error message has to deal with the laser unit polygon motor. On most Brother machines the laser unit does not start up until it starts to print. If the motor does not get to operating speed in a set amount of time then the machine will produce a “Print Unable 71” error message. It is possible that this is caused by failed lubrication in the polygon motor bushing. You can try to S

1. Turn the machine off then back on

2. Replace the Laser Unit or Clean and Lubricate the shaft and bushing with a light weight lubricating oil

3. Replace the Main Board PCB