Stream writer issue ?

First of all indent your code properly, it helps reading.

TextWriter tw = System.IO.File.CreateText(sOutputFilePath + sOutFileName);
if(record == "abcd")
{
	id=10;
	name="John";
	string sout ="";
	sout=id+ "|" +name;
	tw.WriteLine(sout);//output in file1

}
else if(record == "efgh")
{
	id=11;
	name="Sam";
	string sout1 ="";
	sout1 =id+ "|" +name;
	tw.WriteLine(sout1); output in file2
}
else
{
}

Use the debugger to see what your code is doing. We can't test your code as it is not an autonomous piece of code.
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There is a tool that allow you to see what your code is doing, its name is debugger. It is also a great learning tool because it show you reality and you can see which expectation match reality.
When you don't understand what your code is doing or why it does what it does, the answer is debugger.
Use the debugger to see what your code is doing. Just set a breakpoint and see your code performing, the debugger allow you to execute lines 1 by 1 and to inspect variables as it execute.

Debugger - Wikipedia, the free encyclopedia[^]

Mastering Debugging in Visual Studio 2010 - A Beginner's Guide[^]
Basic Debugging with Visual Studio 2010 - YouTube[^]
Debugging C# Code in Visual Studio - YouTube[^]
The debugger is here to show you what your code is doing and your task is to compare with what it should do.
There is no magic in the debugger, it don't find bugs, it just help you to. When the code don't do what is expected, you are close to a bug.

Even simpler to use is File.AppendAllText, see example here: [dotnetperls]
You don't have to worry about opening and closing a stream when you use this.

Thank you all . I have tried your solution, it worked for me.