Удален python3 в надежде переустановить его, но не может этого сделать

$ cat /etc./issue
$ Ubuntu 18.04.1 LTS

Я установил python3.6 и python3.7 из sorces. Теперь я пытаюсь установить gnome-терминал (который по какой-то причине был удален вместе с python3), я запускаю следующую команду:

$ sudo apt-get install gnome-terminal

Эта строка выполняется и выдает следующий вывод:

Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 gnome-terminal : Depends: python3 but it is not going to be installed
                  Depends: python3-gi but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

Он продолжает упоминать python3, но он установлен, я могу сделать:

$ python3 --version
$ Python 3.6.5

Если я попытаюсь:

$ sudo apt-get install python3

Я получаю следующую ошибку:

Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 python3 : PreDepends: python3-minimal (= 3.6.5-3) but it is not going to be installed
           Depends: python3.6 (>= 3.6.5-2~) but it is not going to be installed
           Depends: libpython3-stdlib (= 3.6.5-3) but 3.6.7-1~18.04 is to be installed
E: Unable to correct problems, you have held broken packages.

Если я попытаюсь:

$ sudo apt-get install python3-minimal

я получу:

Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 python3-minimal : Depends: python3.6-minimal (>= 3.6.5-2~) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

И так далее ... что мне делать ?! У меня полностью закончились идеи ...