A 20 days of travel

I just finished a 20 days travel.

20 days of travel.  Alternatively, you can say "a 20 day vacation."  (If it was a vacation and not a business trip.)

Just myself ,a luggage ,a map in on the phone and a pair of comfortable shoes.

You are missing the first part of the sentence here.  What you wrote would be added onto the end of an existing sentence.  I am going to use the phrase "on my phone" rather than "in the phone."  I can't really give you an explanation, but this is how a native speaker would save it.  "In my phone" is not incorrect, but it's strange.  It is better to use "a phone" or "my phone" depending on who owns the phone.  It gives us more information.  This is similar to using "on my phone" versus "in my phone."

"It was just myself, luggage, a map on my phone, and a pair of comfortable shoes."
or
"It was just myself, luggage, a map on my phone and a pair of comfortable shoes."

The only difference here is the comma before the final item on the list.  Both are correct, and it is personal preference.  Usually we find ourselves doing one or the other based on the professor's preferences.
 

I just enjoyed the feeling of a personal travel.

Good!

___Talked with strange people,ate something that____haven't eaten before...

You are missing the subject here.  It should be "I talked with strange people."  "Something that I haven't eaten before."

...and felt every day is a perfect day.

There is a conflict of tense here.  The start is in the past tense, but the phrase ends in the present tense.  There are many ways you could word this.  

"I felt every day was perfect."
"It felt like every day was perfect."
"And felt every day to be perfect." <-- This can get complicated.  I don't recommend doing it this way. 

Make sure that you always have a subject in a sentence.  Unlike Mandarin, we cannot get rid of "I (wo3)" in a sentence.   I think your use of this practice in Mandarin is why you are consistently making the same error.

Always put a space after using a comma!  

A 20 days of travel

I just finished a 20 days journey travel. Just myself, a my luggage, a map in the phone and a pair of comfortable shoes. I just enjoyed the feeling of a personal travel. I talked with strangers people,ate something food that I haven't eaten before and felt that every day was a perfect day.