when I install avast now some of my facebook games do not work
can you help me please
Is it giving any errors or warnings, or just a blank screen?
What did you mean by not working?
Welcome to the forum. 
This is probably related to the Avast Online Security browser plugin.
See if this helps you solve your problem:
https://forum.avast.com/index.php?topic=159528.msg1155084#msg1155084