The phrase "didn't used to" as a negation of "used to" is pretty common in informal English but will also be regarded as ungrammatical by many, especially in writing. There's some pretty good discussion of more acceptable ways to phrase this construction here:
When spoken aloud, "used to" will sound indistinguishable from "use to" for many English speakers.
Actually, "didn't use to" is common in American English, and one shouldn't avoid it at all. If you don't use it, then you're stuck with some formal phrase like, "I formerly didn't" or some awkward phrase like "Before, I didn't..." which is somewhat ambiguous as to the number of times you didn't do something.
"I didn't use to..." is extremely useful in colloquial English, and it's use should be encourage.
On the other hand, "didn't used to" is a double past tense form which just isn't seen in English. You don't say "I didn't gone" you say "I didn't go", "I didn't want" not "I didn't wanted".
"I didn't used to" is bad English.
"Didn't use to" is the correct version. "Didn't used to" is not, although there are some regions which accept it. "Did not used to" piles one past tense on another, and that's not done in English. You say, "I did not go" not "I did not gone" - and "Did not used to" is the exact equivalent of "Did not gone".
You are wrong
A search in the Corpus of Contemporary American English suggests didn't used to appears over three times more often than didn't use to. This may not match some rules of grammar, but it is what people who use English are actually writing.
Here are a couple of quotes from the links mentioned above:
While in American English "did used to" is considered an error, such usage appears to have won some measure of acceptance in British English.
The negative of used to is most commonly didn’t use(d) to. Sometimes we write it with a final -d, sometimes not. Both forms are common, but many people consider the form with the final -d to be incorrect, and you should not use it in exams.
There are so many better ways to phrase this in English, that actually relate more closely to the Russian. Even Yoda would be more clearly understood saying, "Previously, I, such as this, did not dress."
I would suggest the best translations could be:
Previously/Formerly/In the past I did not dress like this/that. I did not dress like this/that before.
Any of those avoid the "use to and used to" argument.
When did раньше become "didn't used to?" It's this lack of translating Russian into what you think English is saying? Besides this sentence presupposes a previous sentence, which is not mentioned here, therefore its impossible to translate this sentence correctly!
No, that's an entirely different verb, meaning "I am not familiar with" "I am not inured to" "I have not become comfortable with". I has nothing to do with some regular pattern of behavior, which "I didn't use to" indicates - I didn't do it in the past, but now I do it.