My 5520 printer keeps saying paper jam, and there is none that I have investigated to see and the carriage willnotmove

SOURCE: How do I get fix a "carriage jam"?

I was able to run run a piece of photo paper through a couple of times and printer now seems to be working again. The theory was that running a heavy piece of paper through might help clear little piece of paper that was not visible. The photo paper is less likely to tear if it gets jammed too.

SOURCE: Printer keeps saying carriage jam

I hate to state the obvious, but maybe your printer has a carriage jam. Fortunately, HP.com publishes a web page that can tell you how to clear the problem:

Carriage Jam Document

Good luck.

SOURCE: printer says paper jam, but no paper in there

use a flash light check all paper path, specially the area around the toner. all you need is a small piece or other (dust). There is a micro switch that detect the paper travel. so if anything preventing the switch to open, you will get error message.
after that, open the toner door, reseat the toner and close the door. the pirnter should return to normal.

SOURCE: carriage jam/officejet G85xi

SolutionStep one: Perform a power reset and connect the printer directly into the electrical outlet Remove all the paper loaded in the main input tray.
Make sure that the product is turned off. 
Disconnect the USB cable from the back of the product.
Disconnect the power cord from the product.
Disconnect the power cord from the electrical outlet and wait 10 seconds.
Reconnect the power cord directly into the electrical outlet and check for the following.
Make sure that the power cord used is the one provided with the product.
If a computer is connected to the product, make sure that the computer is connected to a grounded (three-prong) wall outlet.
Make sure that the power cord is firmly connected to both the product and the power supply.
Reconnect the power cord to the back of the product.
Press the power button ( ) to turn on the product.
Reconnect the USB cable to the back of the product.
If the issue is resolved, proceed to Step six: Print a self-test page.
If the issue continues, proceed to the next step.

for more information please go to below link>>

http://h10025.www1.hp.com/ewfrf/wc/document?docname=c01458822&cc=us&lc=en&dlc=en

Thanks for using FixYa.

SOURCE: Carriage Paper Jam in Photosmart hp c6180 all-in-one-printer

Here's what you do. Take a look at the photo below.
Open the cover of the printer, where the ink cartridges are located. Behind the ink cartridges is the carriage, which is a box that moves side-to-side on a pair of rails. It's the thing that sprays the ink onto the paper.

You have to reach in with your hand and slide this thing to the center. Then, look to the very sides, left and right, for any bits of paper. If you look at the second picture, you can see my finger pointing to a small bit of paper that tore of and got jammed into the side. See the little crumpled bit of paper? It's preventing the carriage from sliding all the way to the right. You could have little bits on the right or left side. I had to reach in with needle-nose pliers to grab the paper bits out, but maybe your fingers are small enough.

Once the little bits of paper were out, I was back in business. Good luck!