Inconsistency with plugins and with the wordpress by itself

I am constantly having consistency problems with WordPress: sometimes is the widgets page that doesn’t load, other times is the customization page, or the plugins page, and so on. Now I can’t even customize my current theme – and I changed it a few times to test if it is a problem with a specific theme; but no, it is a problem with the feature by itself.

What might be happening?
Is there a plugin that I can install to repair errors automatically?

(I use Wamp to access WordPress in a localhost.)