Hi there,
Sorry to hear the printer is acting up :( Here are the steps for a power reset, and you might also want to try cleaning the printhead contacts too as shown in the document I'll link below.. good luck, and please re-post and let me know how it goes...
- Press the Power button ( ) to turn on the product.
- With the product turned on , disconnect the power cord from the rear of the product.
- Unplug the power cord from the wall outlet.
- Wait at least 15 seconds.
- Plug the power cord back into the wall outlet.
- Reconnect the power cord to the rear of the product.
- If the product does not turn on by itself, press the Power button ( ) to turn it on.
http://h10025.www1.hp.com/ewfrf/wc/document?cc=ca&dlc=en&docname=c01661383