@change obviously it should be a "い" at the end of the setence
much more sentence like this , lacking of "い"
like Sentence #83668

どういう意味ですか？

I think it should be "うそを言うない。"　 instead of "うそを言うな。"

標準語では「言うない。」とは言いません。「な」は禁止を表す助詞です。

I m not a native speaker of Japanese , I want to confirm whether that is true , so you really say "忘れな"，”知らな”　”好きじゃな”　 in your daily life ?
In my textbook it says "忘れない"，”知らない”　”好きじゃない”
"not" is not listed in entry of "な" in any dictionary I ve ever referred

We use な like this after a verb to mean don't do something.
するな means the same thing as しないでください, which you have probably already studied.
It's just a different level of formality or politeness.

Here are some other examples you can look at.

[#77191] 話しかけるな。 (mookeee)
[#77551] 列車に乗り遅れるな。 (mookeee)
[#123886] 逃げるな。 (tommy_san)
[#145541] 心配するな。 (mookeee)
[#163414] 私の邪魔をするな。 (arnab)
[#183270] 気にするな。 (arnab)
[#184840] 外見で人を判断するな。 (mookeee)
[#189474] 運まかせにするな。 (mookeee)
[#213769] そう深刻に考えるな。 (tommy_san)
[#218786] これだけは忘れるな。 (mookeee)
[#228090] うらやましそうに彼女を見るな。 (mookeee)
[#236220] 「電車は９時出発だよ」「心配するな。間に合うさ」 (mookeee)
[#1690070] 仕事のことは気にするな。 (mookeee)
[#2135163] その件については心配するな。 (Blanka_Meduzo)
[#3488410] トムのことなど気にするな。 (arnab)

言うな is a negative command (the dictionary form 言う + な).
言うない doesn't make sense.
If you want to say "don't say" in a normal assertive sentence, it should be 言わない (the 未然形 form 言わ + ない).

知らな and 好きじゃな doesn't make sense.
If you want to say "I don't know" and "I don't like ...", you need to say 知らない and 好きじゃない.
If you want to express an unusual negative command "Don't know", it would be 知るな.

忘れな is a positive command (the 連用形 form 忘れ + な). It's a shorter and more informal form of 忘れなさい.
In an assertive sentence, it would be 忘れない.
The negative command "Don't forget" ist 忘れるな.

sorry to disturb you with such low-level "question"
I think I can finally understand this.
I ve searched much in search engine for this, but nothing came out .
Sorry ,again...

Don't worry.

I guess you need to learn verb conjugations. They're not so simple, but once you've mastered them, everything would look quite logical.

Personally, I use ～なよ much more often than ～な.
～な often sounds too abrupt.

Thanks , that would help .