I have had this problem with a few Windows Server 2019: The Start Menu was unresponsive, explorer and other mmc windows wouldn’t open. The following DISM /restorehealth worked for me and will potentially resolve your issues as well.
Remember to always have a backup. Or if its a virtual machine at least a snapshot.
1.Lets get started by Opening up CMD as administrator and running the following:
dism /online /cleanup-image /scanhealth
2. Once /scanhealth is complete, run the following.
dism /online /cleanup-image /checkhealth
3. Now lets mount your Windows Server 2019 ISO as a drive. Take note of your mounted drive letter because you may need to change it to reflect it within this next command. Start elevated command prompt.
dism /online /cleanup-image /restorehealth /source:WIM:d:\sources\install.wim:2 /limitaccess
4. Now run the following to find and repair additional corruption
5. Hopefully all has been repaired restart your server, then run some windows updates and you should be good to go.