How to run Install Repair Mode, How to Un-Install if ?? required for upgrade

[LuigiWriter]

1. How do I start the VirturalBox install in repair mode. I assume I do this in the terminal, but which executable and what argument
This is so I can change the installation from 32-bit to 64-bit.

I read several Forum entries that talked about reinstalling in repair mode, but alas not how they did it. Nor does the user document. None of the 19 executables plainly stood out.

[I mistakenly read somewhere I cannot find that to run windows 32-bit application in VirturalBox that I had to select 32-bit as some stage. now the Guest windows 10 64-bit install program informs me that my Intel i5 CPU's are not 64 bit. Intel says all 4 of them are and I'm not going to argue.]

2. Many applications upgrade without needing to un-install the application being upgraded, others require un-installation first.
Which does VirturalBox require?
The answer to this determines whether I need to un-install, or report a bug. [See Note 1 below]

3. If un-installation is required,[1] the documentation's instructions seem out of date. They are:
------------------------------------
sudo uninstall.sh

which should be in:
/opt/VirtualBox/uninstall.sh
---------------------------------
When I opened /opt/ I found it empty.
I then entered
sudo uninstall.sh
and got "no command" [by that name]

My search of on the VirturalBox download site, or forums yielded no un--install instructions of any version of VirtualBox on a Debian host. [Only on Windows hosts].

[Note 1] because when I tried upgrading to 5.1 from 5.0 I got a message to the effect that the installed version was interfering with the upgrade. Unfortunately it begs the Question, Do I need to un-install, or report a bug.

I look forward to someone's help, so I can continue.

[Perryg]

First thing is to fix the no 64-bit issue. Make sure that you have enabled VT-x/AMD-v ( hardware acceleration ) in your systems BIOS.

This should fix your 32-bit/64-bit issue and you should not need to re-install since I am fairly sure you have the proper "bit" installed. Then we can talk about other issues you may have.