Left country with unregistering in city

I'm having trouble finding information regarding this problem, and I apologize for taking up everyone's time for my dumb mistake. If anyone knows or can link to elsewhere, it is greatly appreciated as I am quite worried about this.
I had studied abroad in Japan between August and December of 2016, and during that time had to register at city hall (in Hirakatashi).
When my study abroad ended, I mistakenly presumed that at the airport upon leaving the country is where I would close my registration. So I was able to leave the country, and they clipped a hole in Residence Card, and that was it. I thought that was all.
(I also said "I am not returning to Japan" when immigration asked. I was on a student visa, and as my semester was over and I hadn't work in line yet for the country, I thought this the right thing to say. Is that going to be a problem?)
Recently though, having spoken with a friend I met while studying in Japan, she told me that you were actually supposed to go back to City Hall and tell them you were leaving the country. I didn't do that--- and is that going to be a problem when I return to the country to work?
I'm worried because I hardly know Japanese, certainly cannot speak about things like this, and where I'll be working is completely opposite from where I'd studied abroad. So not only would handling this by phone be impossible, but I also can't go to the city hall in Hirakatashi and show my old card and try my best to have them understand.

Thank you for your time.

if you say �����s,���{
the information is here
http://www.city.hirakata.osaka.jp/faq/faq_detail.php?frmId=243
what you forgot is �]�o��,tenshutu-todoke.
write those information on an appropriate paper (letter size is preferable.)
you can write in English.
1. the date you left.
2. the place you are living right now. generally, only country name is required. no need to write the detailed address.
3. the previous address in Hirakatashi. need the detailed information.
4. this information is not applicable to you. (for Japanese only)
5. your name, the birth date, year, male or female
6. your IDs. a copy of passport, a copy of Zairyu card, and a copy of health insurance(if you had national health insurance). they will use those IDs to confirm that the applicant is genuine.

make a set of copies before you send them for your record.

the address is :
��573-8666 �����s���� �s����
Shimin-shitu Hirakata City Hall 573-8666 Japan.

"I also said "I am not returning to Japan" when immigration asked."
this is not a problem. they asked is whether you come back to Japan with the SAME visa (residential) status.
when you work in future in Japan, you will have a NEW visa.

thats not a problem. you dont need to worry about it.

they samped you out on your passport and they acknowledged your residence card. you are ok