Quick newbie question

[Lorenzo Bertini]

Dear list,

I found a bug and needed to bisect, so i moved back HEAD to an old 
commit, then configured and built. I went back to master and can't build 
anymore because its missing `nod.hpp` file; no git command seems to 
restore this file (git reset --hard, creating a new master branch 
tracking origin/master, etc).

I would like not to clone again as its very slow, but all I find on the 
internet are commands I already tried. What should i do?

Thank you in advance,

Lorenzo (lynx)