Hi, mjw_921
Welcome to Microsoft Community.
We understand that you have encountered the problem that Windows 10 Alt+PrintScreen can't be used. The reasons for this problem may be related to the interference of third-party software, system settings and user profile failures. I suggest you try the following methods: I. Check Windows system settings.-Open Settings → Easy Use → Keyboard.-Find the option "Use the PrtScn button to open a screenshot".-If this option is ON, turn it off.-Test whether the shortcut keys are restored after restarting the computer.II. perform a clean startThe method is as follows1. Click Windows+R and enter msconfig.2. Open the system configuration and select the General tab-selective startup.3. Remove the check of loading startup items.4. Go to the Services tab-click Hide All microsoft Services in the lower left corner, and then click Disable All.5. Click OK and restart the computer. (Please be sure to hide all microsoft services first, and then click Disable All, otherwise it may lead to unforeseen problems such as being unable to enter the system.)See if the problem will recur.*Disclaimer: A “clean boot” starts Windows with a minimal set of drivers and startup programs. It helps to determine whether a background service is interfering with your game or program and to isolate the cause of a problem.**These steps of "clean boot" might look complicated at first glance. However, to avoid any trouble for you, please follow them in order and step-by step so that it will help you get back on track.*III. Try to create a local account and then try it in a local account. Does the problem still exist?Search for CMD, then run in administrator mode and enter the following commandnet user USERNAME PASSWORD /addnet localgroup administrators USERNAME /addUSERNAME PASSWORD can be replaced with the account name and PASSWORD you want, and password can be omitted if no password is needed.If there is no problem under the new account, it should be a fault in the account configuration file. Please refer to the scheme under "Fix a corrupted user profile" in the following article to transfer your data to the new account.* Troubleshoot Problems Signing In to Windows - Microsoft Support *If you have any progress, please feel free to contact us.
Best Regards
Nicholas.Z - MSFT | Microsoft Community Support Specialist