Hi,
Did you updated the .Net on the server? If yes please follow these steps and verify the mode of the .Net by following below steps for exact version of .Net you have installed:
Check if .Net 2.0 is set to run in 32 bit mode. Executing ldr64.exe query from C:\Windows\Microsoft.NET\Framework64\v2.0.50727 will return 0x0000000 if set to 32 bit mode. To set it to 64 bit mode, execute ldr64.exe set64, which should return 0x0000001.
try launching servermanager.exe
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