How to modify Windows System Registry Values with C#? As usual, you need to use Microsoft.Win32 Namespace ~ using Microsoft.Win32;. Let’s take Windows Application Event Logs values as an example. I want to change the MaxSize and Retention values in Application Event Log file by using C#.
Codes to change Windows System Registry values
RegistryKey TestEventLog = Registry.LocalMachine.OpenSubKey(“System\\CurrentControlSet\\Services\\EventLog\\Application”,true);
TestEventLog.SetValue(“MaxSize”, “102367232″, RegistryValueKind.DWord);
TestEventLog.SetValue(“Retention”, “0″, RegistryValueKind.DWord);
Above codes open Application event log and with write permission (,true). It changes both MaxSize and Retention values.
Just change the codes to suit your need. 
