This is some ... interesting code. You may want to consider using consistent naming conventions as well as more intuitive return types.

In your first example, you're sharing a single variable within the scope of Get_Saves, @files. In the second example you're set up to use multiple copies since you're returning @files and assigning it to another @files variable as the result of the call to find. But at the same time you're trying to pass a reference to the @files in the scope of Get_Saves. These two mechanisms are in conflict.

One version:

sub Get_Saves {
    my @files;
    @files=find(\&FileName,"/usr/local/apache/htdocs/service/"); #sure
+ you want to hard code this?
    return  \@files, $#files+1; # why return the size?
}##END Get_Saves

sub FileName {
    my @files;
    unless (($_ eq "." )or ($_ eq "temp.svd")){ # do you need to test 
+for '..' too?
        push @files, $_;
    }
return @files; 
}##END FileName
[download]

Another version:

our @files; # globally accessible

sub Get_Saves {
    @files=find (\&FileName,"/usr/local/apache/htdocs/service/");
    return  \@files, $#files+1;
}##END Get_Saves

sub FileName {
    unless (($_ eq "." )or ($_ eq "temp.svd")){
        push @files, $_;
    }
}##END FileName
[download]

I don't believe that find (\&FileName(\@files)) will work because you're passing a reference to the subroutine, not invoking it.