Question Mouse and keyboard stops working after going into Startup Repair

[Phoenix_OS25]

Recently my high school gave me 4 old HP office desktops that they weren't using. While trying to do that trick of going into startup repair and opening command prompt to log into administrator on Windows 7 Professional, my mouse and keyboard stops working to were I can't select anything in startup repair. So now I'm completely stuck, my mouse doesn't even show up on the screen. I've tried looking it up on YouTube or any where else but nothing pops up. Does anyone else know how to fix this problem? Thanks.

Here's an example image of what I see, instead of the mouse pointer being there.

 

[RARRAF]

I think what you need is one of these: PSU to USB Adapter

 

[Phoenix_OS25]

I think what you need is one of these: PSU to USB Adapter

Maybe, but I've done it once without that and it never happened.