In addition to post #9 above yours, see here:
Will win 7 problems/corruption prohibit upgrading to win 10? - Windows 10 Forums
I hope the laptop was not volume licensed through her school, that would make this complicated. Anyway, I doubt that.
EDIT: Saw you posting it's Windows 7 Home, it can't be volume licensed so the above is of no concern.
You should find the correct product key in so called COA sticker, usually located on bottom of the laptop, sometimes hidden under the battery:
See this tutorial for instructions in clean installing Windows 10 using your Windows 7 product key: Clean Install Windows 10 Directly without having to Upgrade First - Windows 10 Forums
Exiting from that situation is only possible with repair or clean install, even repair does not work in most cases because setup is still reading instructions from answer file that wont work.
As it is now, OP has no chance to get to Windows 7 desktop to download ISO, mount it and start upgrade.
If sysprep command was run without /unattend:PATH_TO_ANSWERFILE switch, no answer file would be used except if folder C:\Windows\System32\Sysprep contains one with exact name unattend.xml.
If sysprep was run with /unattend:PATH_TO_ANSWERFILE, it can be located anywhere and have any name.
In this OP's case, in both above scenarios it will be located on the Windows 7 laptop. Theoretically it could work to boot the laptop with a WinPE media, remove the answer file and reboot; however this fails more often than works.
In any case I would no longer even try to rescue the underlying Windows 7 because a failed sysprep has already left it marks.
Yes, Kari, I meant to ask you :-). Thanks for the answer! You are the sysprep and VM guru. Kyhi is the PE guru. (Although you might very well be a PE guru too!)
Thanks people for your answers. I'm still at work for another 5 hours and then home and straight to bed.
I have been toying with giving her a couple larger hdds as the 2 she has in there now are both only 20 GB.
Had another look at her hdd and she has 2, one x 500G C drive which has the W7 OS on with 3 different partitions and one x 20G D drive which has very little on it but is full.
Should the OS be on the smaller 20G drive and all downloads, programs etc be stored on the bigger drive?
If it were me, I would replace the 20GB hard drive with a 120gb SSD and install Windows 10 to that.
But, no the OS should not be on the 20GB hard drive, you would have to very carefully clean it to keep enough free space to install updates.
Thanks for that answer, I better go and buy one before I waste any more time trying to get W10 installed.
I dropped into a pc store on the way home from work today, but they advised that I should take out the old hdd to see if the latest SDD are compatible with the laptop.
I attempted to remove the base of the laptop but it did not want to just separate easily. I chickened out as I really didn't know what I was doing. She is back to school tomorrow.
I think her old man should be going back to school?