try this mate it helped me get it working

1. Do you have rootsh installed from the Repos?

the command sudo gainroot will only work if it is. Hence the error message. if not, install and then reboot.

2. When you now type sudo gainroot, it should return

/home/user #

3. Seems you have some broken dependencies. To repair this run

apt-get -f install

before you do anything else. This command should work!

4. Then run

apt-get clean

5. Finally try again to install qtwrt