First of all, let’s fix your question. It should be: “Why can’t I use ‘know’ and ‘want’ in the past progressive?” Before answering your question, please make a note to be more careful not to mix up “can” and “can’t”, and make sure to study the formation of questions (using inversion of the subject and verb). That said, we can use “know” and “want” in all tenses, aspects, and mood, but verbs of state are usually *not* used in the progressive aspect. This is true in Spanish as well; we usually say “sé algo”, not “estoy sabiendo algo”. The same is true in the past progressive as in the present progressive (and future progressive, perfect progressive, etc.). Nevertheless, it is possible to use the progressive aspect if we want to emphasize the *dynamic* nature of the verb (that is in progress): For example, “I’m really wanting pizza right now” means that you are actively desiring pizza at the moment. Note that stative verbs like “know” and “want” often translate into the Spanish imperfect (sabía / conocía, quería). If you mean supe, conocí, or quise, we would often use a different translation, perhaps “found out” / “met”, or “tried to”.

No se entiende

I would like to help sorry but what is kwon?

I think you mean "know", which is a verb that **cannot** be used in any progressive form. Here's a list of verbs that cannot be used in progressive forms https://www.englishpractice.com/grammar/verbs-progressive-forms/#:~:text=Some%20verbs%20are%20never%20used,understand%2C%20want%2C%20wish%20etc.