For now what you should do is get leafpad and open the .desktop file with leafpad and remove the sudo from the code. That way the app should work but it won't be able to save preferences.

Oh wait, you won't be able to do anything without root access, the .desktop file can't be saved. I don't know what to suggest.

My guess is you are missing dependencies that is causing rootsh not to work properly, if rootsh was installed properly it wouldn't ask for password while trying to execute any command with root access and checking for missing dependencies would require you root access:

apt-get -f install
or
apt-get check

etc can't be executed without root.

Few more ways I am aware of is to transfer edited .desktop file using putty or filezilla but that would need mad developer and I guess it depends upton rootsh or alike.

I would say remove rootsh and reinstall it using application manager.