I didn't've not been writeing here for the past 2 weeks ago, or something like that.

(1) For the first part of the sentence, I think the present perfect continuous tense is more appropriate here (as opposed to the simple past, which you used). This form is used when talking about an action that started in the past, and continues up to or ends in the present.

(2) We don't use "ago" with "for". "2 weeks ago" might refer to just a specific day from 2 weeks ago, while "the past 2 weeks" refers to the entire period of 2 weeks.

Maybe I was too busy, or (I) just I forgot about it, I'm not sure.

(1) The placement of "I" is wrong. In this case, you can also omit it entirely, since the phrase already shares the subject with the previous phrase "maybe I was too busy".
(2) I think "forgot about it" sounds more natural here.

A lot of things happened on this time,. I did my routine as normal,: I went to the gym, I ate healthy and I continued learning English every days, maybe I didn't. I might not have been writeing on LangcCorrect, but I continued improving my pronunciation, reading and, majority I wasost of all, improving my listening by watching videos, documentalries, and movies in English.

(1) I broke this lengthy sentence into multiple smaller ones to improve the flow of the writing.
(2) "As normal" seems okay, though "as usual" is probably more common.
(3) Omitted some instances of "I" to avoid excessive usage of the word, which can make the writing sound stiff.
(4) Strictly speaking, "LangCorrect" is the correct capitalisation.

Yesterday, after almost three months without any contact, I talked with my ex -girlfriend,. I tookmade the decision tof talk to her because I saw a sadness stuff i post on her TikTok,; it wasn't a sadness stuff only to her but also for me.

(1) Again, I broke this sentence up into smaller ones to help with flow.
(2) The phrase is "make a decision".
(3) Made some other general tweaks so the writing sounds more natural and fluent. "Sadness stuff" is quite an awkward expression.

Her cat died and I couldn't ask forabout it, because it was like my son when we were together.

The phrase is "ask about (something)". "Ask for (something)" refers to the act of asking someone to give you something.

We only spoke about it.

This is somewhat contradictory with the previous sentence: you couldn't ask about the cat, yet the two of you spoke about it? Unless my interpretation of the previous sentence is incorrect of course, in which case please do correct me.

I'll try to return to LangcCorrect and write every days.