Light extremely dark following Windows 10 upgrade

Had the Windows 10 “April Upgrade” a couple of days ago. Now all the lighting in the games I’ve been working on are extremely dark and unplayable. The resolution now seems poorer quality but without enough light I cannot see clearly.

I’ve re-installed the most recent Nvidia drivers for my laptop in case it was a Windows / Nvidia problem - no difference.

Please help, this is making all my work to date useless.

Ray