Virus definitions won't update

My Software version is 19, so I need AVG Clear, but this app won't run on my PC

Hello Ali. It seems an instance of AVG installer setup is running in the background. We'd request to restart your PC once and then try to apply the fix.

If you need anything else, do not hesitate to let us know.

Virus definitions says it needs updating, but when I try, it just runs indefinitely, saying it is updating. I found a fix here, but when I click to uninstall avg, it says "setup is already running. Please try later"
Hello Ali. It seems an instance of AVG installer setup is running in the background. We'd request to restart your PC once and then try to apply the fix.

If you need anything else, do not hesitate to let us know.

Same thing happens after restart

But it won't let me do the repair!
That's when it says "Setup is already running. Please try later"
Restarting computer hasn't helped

My Software version is 19, so I need AVG Clear, but this app won't run on my PC

Thank you for the info, Ali. 
Please restart your device in safe mode: https://support.avg.com/SupportArticleView?urlname=AVG-Restart-Windows-Safe-Mode and then proceed with the clear and remover tool. 
We recommend you to use both tool to uninstall AVG with its traces. After restart, go to Run window (press windows key and R key simultaneously) and type the following comments to delete the folders manually.

1. Type  “Temp” and press enter, remove all the files.
2.  “%temp%” and remove all the files.
3.  %appdata% - Remove all the AVG folders.
4.  %programdata% - Open the AVG folder and remove the old files.
5. Type C: and press enter, delete AVG remover folder.

Please go to c: drive-> program files and delete the AVG files. Reinstall AVG from our official site: https://www.avg.com/en-us/installation-files

This isn't the expected behavior.
It seems that the AVG services doesn't respond or stops.
Hence, we request you to run AVG clear followed by AVG remover tool as mentioned in this article.
This will help you to remove both old and new version traces of AVG antivirus.
Once it is completed, install AVG antivirus free as mentioned in this article.
Keep us posted.