Personally I only see reinstalling a game as a last resort, shouldn't be required in 90% of all problems that occur. (Personal opinion)
Now, not exactly sure which one of these scenarios you got problems with:
You see all animations properly, but you cannot perform the attacks yourself.
Or...
You can't see any animations, only yourself standing there with arms and legs stretched out, but other people see you do the attacks properly.
If first, not sure, doubt that's your problem but if it is, maybe it has something to do with the plugindisable settings, or plugin version.
If second, to see the animations you need the client plugin. And to be exact, you need the file named "japlus_gla_anims.pk3".
Also, you need to have this file in your base folder, not japlus folder. Basically it's the file with all the animations. So without this file in base, you won't see the new animations!
In the event of you actually having this file in your base folder already:
Your problem must be from having more than 1 animation modifying pk3, either in your japlus folder, or in base folder.
If you know of any mod you installed in the past that might cause this, try removing it. And if you have no idea which pk3 can cause it. Find a pk3 with models/players/_humanoid/_humanoid.gla file in it.
The _humanoid.gla file being the file which contains animations. Find the pk3 which is NOT an assets file or japlus_gla_anims.pk3, and remove it.
Hope this helps