C4345 shows missing cartridges

[C4345]

I would like to know other options to resolve my printer's problem. It shows missing cartidges at the small screen. my printer hasnt been used for 3 months. i cleaned the copper thing because that was what i read that i should do. but tha didnt help. same message still shows at the small screen. 

[A4Apollo]

Hey there! @C4345, Thanks for stopping by HP forums!

I understand your printer shows missing cartridges on your printer.

Don't worry I will try to help you out.

Did you make any changes to your printer?

Please try the steps recommended below.

Follow these steps to reset the printer.
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.

Refer this article to further troubleshoot Print cartridge missing.

Let me know if this helps!

Have a wonderful day ahead! 🙂