I tried the git reset --hard HEAD@{n} from git reflog and I lost everything with my current unstaged files :'(
the unstaged files is the last git add I did, before then I tried git reset to the last git commit.
And all my files gone, I can't go back to the git add before last commit :'(
It's not clear if you lost files in your working directory, or files in the index. You say you lost your "unstaged files", but then you mention you might have run "git add". "unstaged files" are lost for good.
Staged files can be recovered with
git fsck --full --unreachable --no-reflog
For each file added there will be a lost blob object, and for each directory entry there will be a tree object. You would recover your file changes by doing
git cat-file -p SHA
For each file that you had modified
(master)$ vi bar
(master)$ vi baz
(master)$ vi foo
(master)$ git add foo bar baz
(master)$ git reset --hard HEAD
HEAD is now at ead8fa2 initial
(master)$ git fsck --full --unreachable --no-reflog
Checking object directories: 100% (256/256), done.
unreachable blob 0c29287001b29159f11c4e8a320bce7e9789c00b
unreachable blob 1524d3478e3d0b92866a53239b10bcd4b3838c4d
unreachable blob 97b724e770249816c61d8a526415986208ed7e15
// take a look at one of the objects
(master)git cat-file -p 0c29287001b29159f11c4e8a320bce7e9789c00b
changes for bar
//Here, based on inspecting the output, I can determine that 0c29287 was the file "bar"
(master) git cat-file -p 0c29287 > bar
(note I didn't get any lost trees when I tested, so this part may not work)
If you modified a whole bunch of files it is probably easier to recover via the tree object instead of individual files
git read-tree SHA
Where SHA is the lost tree object for the root tree.