Hi ,
Welcome to HP Forums, this is a great place to get support, find answers and tips.
Thank you for posting your query. I'll be more than glad to help you.
I understand that you are facing issues with your HP ENVY 7640 e-All-in-One Printer wherein you get an error message "There is a problem with the printer. Turn the Off, the On."
This could be a hardware issue with the unit.
Let's go through a few steps that may help to fix this issue.
I suggest that you follow the step by step guide listed below to reset the printer:
1.Disconnect if there is any fax or USB cable connected to the unit and then turn the printer on, if it is not already on.
2.With the printer turned on, disconnect the power cord from the rear of the printer.
3.Unplug the power cord from the wall outlet.
4.Wait at least 60 seconds.
5.Plug the power cord back into the wall outlet.
NOTE: HP recommends connecting the printer power cord directly to the wall outlet.
6.Reconnect the power cord to the rear of the printer.
7.Turn on the printer, if it does not automatically turn on. The printer might go through a warm-up period.
8.Wait until the warm-up period finishes and your printer is idle and silent before you proceed.
If the issue persists, you may update the firmware from the link: Firmware Update
If the issue still persists, then I suggest that you contact HP Technical Phone Support from this link: http://hp.care/2r9wSvP
Select the country where you are located and type the product# or the serial number of the unit and then choose the 'Contact Support' tab at the top and scroll down to the bottom of the 'HP Support- Contact' page to fill out the form provided with your contact information. Click on 'Show Options' icon and then scroll down the page and select 'Get Phone Number' to get the phone number.
You have a good day ahead.