Rescuing data not working - are my data gone

[jaykinse]

An AVG disk checker corrupted my boot files. I'm currently trying to rescue my data to an external drive before I reinstall the OS but it's been stuck on 0.00GB for hours and there is no option to cancel. Apparently if I wait another 490 hours the 87GB will be rescued (I think I could type all the 1s and 0s more quickly than that) ... but at this point I don't believe it will do anything. 

If I hold down the power button and switch off my laptop, will I lose all my data?  Or do I at least need to wait for the cancel button to become a clickable option?  When will that appear?  But will that also have a negative effect?

EDIT: I have an SVE14AG15M. MS recently forced a Windows 10 install on it, which nearly killed it, and I restored to 8.1 soon after. It has been very slow and temperamental since then, hanging regularly. 

[jaykinse]

25GB of 87GB now copied to the external drive.  

Can anyone prepare me for the next step? What happens when the data rescue is completed, assuming it is successful?  Will it then repair the OS and give me back a functioning PC?  Or is the rescue done in isolation, and do I have to do something else to fix it?  Will I need to recover the OS from the backup I have created?  I hope not, as I don't want to risk that - I have nowhere else to transfer my (hopefully) newly-rescued important files. (The whole point of a repair and recover is so that I don't have to buy a new computer.)