how to make a validation like vb in asp.net? I want to make a text box should only accept numeric values....
First of all you need validation for textbox and you want user to enter only numeric values. So rather than allowing user to enter something and check it whether it is numeric or not is not good approach. I believe prevention is better than cure.
So you can Use FilterTextboxExtender that comes with AjaxToolkit. Please have a look at this demo
I hope this will solve your problem. You can use other tools also, they are very useful.