Sure, mistakes happen. But only in exceedingly rare circumstances will I undo a downvote. If you would like to issue an appeal, shoot me a private message explaining what I got wrong. I tend to respond to Reddit PMs within several minutes. Do note, however, that over 99.9% of downvote appeals are rejected, and yours is likely no exception.
How can I prevent this from happening in the future?

Accept the downvote and move on. But learn from this mistake: your behavior will not be tolerated on Reddit.com . I will continue to issue downvotes until you improve your conduct. Remember: Reddit is privilege, not a right.

I just downvoted your comment.
FAQ
What does this mean?

The amount of karma (points) on your comment and Reddit account has decreased by one.
Why did you do this?

There are several reasons I may deem a comment to be unworthy of positive or neutral karma. These include, but are not limited to:

Rudeness towards other Redditors,
Spreading incorrect information,
Sarcasm not correctly flagged with a /s.

Am I banned from the Reddit?

No - not yet. But you should refrain from making comments like this in the future. Otherwise I will be forced to issue an additional downvote, which may put your commenting and posting privileges in jeopardy.
I don't believe my comment deserved a downvote. Can you un-downvote it?

Good evening.
No matter how small I make it, Steam says the message is too big.
Perhaps the beautiful hearts and souls found in Equestria are indeed much too large to fit in a Steam comment. Regardless, I must share this vital telegram. Please, take a look, and pretend it fit in the comment box: https://pastebin.com/gDZwtu52

WARNING! Carry on reading! Or you will die, even if you only looked at the word warning! Once there was a little spaceman called Clarissa. She was 17 years old and she lived in a permabrig, because she killed her mom and her dad. She got so bad she went to kill all the staff in security so nanotrasen decided that the best idea was to get rid of her, so they set up a special room to kill her, as humanely as possible, but it went wrong, and the machine they were using to kill her malfunctioned, so she sat there in agony for hours until she died. Now every week on the day of her death, she returns to the person that reads this message, on a monday night at 13:01.

She creeps into your dormitory and kills you slowly, by cutting you and watching you bleed to death. Now send this to ten other pdas on this one station, and she will haunt someone else who doesn't. This isn't fake. apparently, if u copy and paste this to ten messages in the next ten minutes u will have the best luck of your life.

Boy: No
Girl: Do u even like me?
Boy: No
Girl: Would u cry if i walked away?
Boy: No
She heard enough and was hurt... She walked away with tears in her eyes
The boy grabbed her arm
Boy: Your not pretty...your beautiful
Boy: I dont want to be with u forever...I need to be with u forever
Boy: I dont like u...I love u
Boy: I wouldn't cry if u walked away......I would die if u walked away.
Boy Whispers: Plz stay with me
Girl: I will...
*Tonight at midnight your true love will realize she/he loves u
*Something good will happen to u at 1-4pm
*Tomorrow it could be anywhere!!!
*Get ready for the shock of your life!
*If u dont post this to 5 other comments... You will have bad luck in relationships for the next 10 years

12 things your doing:
1. Your reading my comment
2. Now your saying/thinking thats a stupid fact.
4. You didnt notice that i skipped 3.
5. Your checking it now.
6. Your smiling.
7. Your still reading my comment.
8. You know all you have read is true.
10. You didnt notice that i skipped 9.
11. Your checking it now.
12. You didnt notice there are only 10 facts Copy and paste to 1 Profile, tomorrow will be your best day ever! no matter what!

❤¸.•""•. ¸❤ ❤¸.•""•. ¸❤ ❤¸.•""•. ¸❤ Post this on the walls of the 12 prettiest Girls you know... If you get back 5 you're beautiful. .. ❤¸.•""•. ¸❤ ❤¸.•""•. ¸❤ ❤¸.•""•. ¸❤

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Gained 5 toes

+ rep chill killer :)

+rep, The best irish breakfast i have ever seen :D

+rep cutie patooie

+rep nice drunk killer

-rep girl the way you ignored taurie at the start, picking favourites

-rep

Idiot

Has 30 days left to live

Fat

pretty sadistic deathslinger but let me out, occasionally broke my crouch button with him

+rep qt

+rep very nice, very cute xeno

+rep good sport

-rep

Hi

+rep triple the normal amount of chromosomes

triple d would be proud

Has 4 balls