I tried upgrading to Ubuntu 16.04.1, not sure exactly what happened but it didn't finish. 

I am now having problems with apt-get. `/usr/bin/dpkg` is empty. Is there a way I can replace the contents of that file in order to get apt-get back to running? 

When I do `dpkg -l` I get: 

```
The program 'dpkg' is currently not installed. You can install it by typing:
sudo apt install dpkg

```

When I do `sudo apt install dpkg` I get:

```
Sub-process /usr/bin/dpkg returned an error code (100)

```