Hi Dhiraj,
You need only to loop your matrix rows and reset the U_Number value
under the event After Menu Pressed of delete ('1293').
For Add Row is more simple. Just add get your last matrix row number and set the value of U_Number as the Number of Rows in the matrix. under the event After Menu Pressed of AddRow ('1292') and anywhere in your code that you add a row programmatically.
The code will depend on what type of datasource you are binding your matrix with.
Regards
Edy