Saar Carmi shows how to do this in his sample found on C# Corner. In it, he uses the Process class in System.Diagnostics to implement this functionality using code such as
public static Process RunningInstance()
Process current = Process.GetCurrentProcess();
Process processes = Process.GetProcessesByName (current.ProcessName);
//Loop through the running processes in with the same name
foreach (Process process in processes)
//Ignore the current process
if (process.Id != current.Id)
//Make sure that the process is running from the exe file.
if (Assembly.GetExecutingAssembly().Location.Replace("/", "\\") == current.MainModule.FileName)
//Return the other process instance.
//No other instance was found, return null.
Public Shared Function RunningInstance() As Process
Dim current As Process = Process.GetCurrentProcess()
Dim processes As Process() = Process.GetProcessesByName(current.ProcessName)
'Loop through the running processes in with the same name
Dim process As Process
For Each process In processes
'Ignore the current process
If process.Id <> current.Id Then
'Make sure that the process is running from the exe file.
If [Assembly].GetExecutingAssembly().Location.Replace("/", "\") = current.MainModule.FileName Then
'Return the other process instance.
'No other instance was found, return null.
End Function 'RunningInstance