Alt tab problem

Hi guys need help here

Hi im not good at pc stuff but I have a annoying problem, so everytime I play some game ie dota/csgo on my pc everytime I alt tab to desktop im stuck on a black screen with power and running apps on the back ground. There is power but no display monitor is on with power
 
Alt-Tab shifts from active program to another running program in the background... give it another program, like 'file explorer'... and see if you can shift back and forth.
 
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