Sometimes on Windows operating system window+print screen not working. To fix windows+ print screen follow the following steps
Enable PrintScreen option
Sometimes print screen option is not enabled. To enable print option go to settings > ease of access >keyboard> enable PrintScreen option
Try an alternate method
Sometime window+printscreen not working so they can use an alternative method to take screenshots.
- Press the Print Screen button. (this will copy screenshot)
- Open Paint or any photo editor software
- Then paste your screenshots shown on the photo below.

Update your window
If nothing is work for you then update your window definitely work for you.