Android Studio select deployment target

Question

I was working on some app and had a device connected to the the computer, also I had an emulator, both of them worked properly. I d'ont know what happend but now I cant see any of them. It says "nothing to show" when I open the window of "select deployment target"(after I click run). What can I do?

This is the message :

Fixed

I went to the task manager and ended the process named adb.exe, and it worked.