Just lost every important files in my Trisquel Linux!!!! Very serious!

I tested your command with:

find -name "*.c" | less

... And got every good match, except ".bashrc".

You must have used:

find -name "*c"

... to result in such a mess.

Every time I work with the command line, I do multiple tests to make
sure things would work as expected, and since I'm slow, it takes some
hours to get things running the way I intend them to. Still, even after
testing, some times they work as intended, and other times I have to
test again.

The command you mention removes all .c files/directories in the working directory and below, unless you mistyped it like other members of this forum wrote. If you did not mistype the command, then you must have done something else that led to the involuntary remotion of many of your files.

If you create a directory and a file like this

mkdir 'x ./'
touch 'x ./ x.c'

and try the find command, you will have a match

x ./ x.c

Now if you pipe this into xargs rm you don't have just one path. You have three

x
./
x.c

The middle one is the current directory. So all will be gone.

You are right. The command is not safe.

But you should anyway understand a command before using it.

The sudo command seems pointless here. Giving recursive flag (-r) to rm doesn't make sense since you seem to have been only trying to delete files, not whole directories. In the example I gave having rm without the flag would only delete the .c file.

Hope you get your files back.

You probably have spaces in your filenames (perhaps your home directory). In this case, not using -rf would have mitigated the damage.
But, you shouldn't use xargs with find. Instead, use the -exec option like this:
$ find . -name '*.c' -exec rm {} \;
That way, you don't have to worry about spaces.

If you have a backup, just use that. Otherwise, try using photorec: http://www.cgsecurity.org/wiki/PhotoRec

By default xargs uses both spaces and newlines as item delimiters. The -d "\n" option tells xargs to use only newlines as delimiters, thus avoiding this problem in this context.
$ find ./ -name "*.c" | xargs -d "\n" rm

To add to what jbar suggests, it's even better to write:

find -name '*.c' -print0 | xargs -0 rm

Doing it this way should be even safer since names may have new lines in them (almost never in reality, but it's possible).

I would also suggest adding an echo before rm or any other command you run in this way, so you can see what's going to be done before doing it:

find -name '*.c' -print0 | xargs -0 echo rm

Thank you all for the replies, thank you very much!
But first of all I want to apologise to ADFENO. What I said it was not right, i Admit. Even if I was furious due to that event it was no way an excuse to talk to somebody like that. Sorry ADFENO and sorry to all the Forum.
Desculpa colega, voce tem ajudado sempre aqui no forum e eu fui ingrato e mal educado com voce. ao deveria nunca ter dito o que disse: Desculpa.

Thanks I will continue to make questions if there are any. Abracao

One thing you could do to prevent such accidental data loss
in the future is changing the default behaviour of the rm command for example with aliases.

This is what i have in my /etc/bash.bashrc to do this job:

alias rm='rm -div'
alias rrm='\rm -IRv'

alias mv='mv -iv'

alias cp='cp -iv'
alias cpr='cp -r'

I've never had any problems with these.
There is also to mention the package safe-rm in the repository, but i never tried it.
Take a look at the info or man pages of rm, mv and cp to see what exactly all these options do.