I want to find an approach to identifying my print problem. I am running Ubuntu 16.04 LTS on a laptop. My printer is a Canon PIXMA TR7520. I am trying to connect using my home wireless network. This function had been working, but now it is not. Print jobs sent to this printer across my home network from other devices successfully print. The print status dialog box in Ubuntu indicates the job status is "processing", but the printer does not respond. Thank you for your help.

The printers IP change? Will it answer a ping?
What did you change?
https://www.canonsoftwaredriver.com/...driver-manual/

Check the printer's status in CUPS (http://localhost:631) to make sure it's accepting jobs and not paused or something.

Let us know current printer status reported by CUPS...

The IP address has not changed. It does answer a ping.

lpstat -t

replies with

scheduler is running
system default destination: Canon-TR7500-series
device for Canon-TR7500-series: dnssd://Canon%20TR7500%20series._ipp._tcp.local/?uuid=00000000-0000-1000-8000-0018243061ba
Canon-TR7500-series accepting requests since Tue 20 Aug 2019 02:03:01 PM CDT
printer Canon-TR7500-series is idle. enabled since Tue 20 Aug 2019 02:03:01 PM CDT
The printer is in use.

I have not knowingly made any changes.

I had previously shut down and unplugged the computer and shut down the printer and restarted them without resolving the problem. The printer "in use" status led me to try shutting them down again and unplugging the printer for a few minutes. That resolved the problem. After starting the computer and the printer, the printer status became "idle". The print function now works.

Thank you for your help.

Good to read of your success with this. Thanks for the update.