It's CTRL+ALT+DEL to open Task Manager.
I'd probably go for a repair install for this which won't affect your personal stuff or installed programs.
You will need to create a Win 10 install disk or USB if you don't already have one which you can do at
http://windowsiso.net/Hover over the Win 10 ISO tab then hover over the version for your version then click on Standard where you get the option for 32 or 64 bit.
Select Save on the download then use
https://www.microsoft.com/en-us/download/details.aspx?id=56485 to create a bootable DVD or USB.
To perform a repair install, with the machine booted up, open Windows Explorer - This PC - insert the install media and double click on its drive.
This will start the process if using a DVD but will open to its files when using an USB, where you would then double click on setup Application.
This takes a little over 3hrs on my Win 10 Home x64 and reverts the apps to default and may turn off System Protection which you will then need to turn back on.
It may be that some of your drivers are out of date that is causing the black screen on updating versions.
It may be that Windows can find updated drivers for you but generally you may need to go to the driver vendor's site, except in the case of Nvidia graphics, as they can be OEM modified if you are using an OEM branded machine.
To see if Windows can find any, go into Device Manager/View/Show hidden devices then work your way through each section by right clicking on the items and selecting Update Driver.
It could be a graphics driver that needs updating or one of the items in System devices.
