Hello Erika,
I understand the inconvenience.
Try (repair) of AVG Internet Security and check the status.
If the same error appears, provide the (screenshot) of error message to assist further.
You can post the screenshot here in your topic. Click on 'Answer' & then click on the 'Image' [mountain symbol] & follow the instructions.
I can not open AVG Internet Security. I get an error message stating: The procedure entry point could not be located in the dynamic link library C:\Program Files (x86)\AVG\Antivirus\AVGUI.exe
How do I fix this please?
Thank you the repair worked. 
You are most welcome and thank you for updating the status.
Since we had a bug with the user interface, you were facing this issue.
This was fixed through latest 18.4 version release.
Hence, the repair has resolved the issue.
Feel free to contact us if you need assistance with AVG.