Ok I know what the f**k so I'm explaining if someone have the same problem. It was some kind of bug that made NMM not responding. So how to fix it: Go to "Download Menager" at the bottom of your screen ---> Cancel all actions
As in the title "Add Mod from File" is not working. What i do: Click "Add Mod from File" Button ---> Select Mod ---> Click "Open" Button ---> ??? WTF?! Nothing happens...