Hello,
I'm writing this because I the answers given here, and in other forums, didn't specifcally help me. I have an older computer and in my case I needed to download an older version of the Citrix client which I found on the below website under Client Installation issues.
http://www.ardamis.com/downloads/XenAppWebPlugin11.0.150.exe
Having gone through several other fixes, I then needed to reset the association for the launch.ica folder to Citrix Client Connection (may also be listed as Citrix ICA Connection). Open an explorer window then go to Tools--> Folder Options--> File Types.
After that, I was able to use the following fix found on this website and it worked.
Open a command prompt in the same directory wfica32 resides (i.e. C:\Program Files\Citrix\ICA Client) and run the following command; wfica32 /setup