ajax is not working

i have a web application and in this i am using ajax controls. due to some problem i remove the reference of ajaxcontroltoolkit and reset the toolbox of visual studio. After some i again add reference of pre开发者_如何学编程vious ajaxcontroltoolkit and add tab in visual studio toolbox. Now problem is that when i insert the control of newly installed ajaxcontroltoolkit and run the webapplication the no event(which is in update panel) or no ajax validation fire. so please help what should i do lot of time i try and remove and add reference of ajaxcontroltoolkit but not working.

Try manually deleteing the AjaxToolkit.dll file from your Bin directory.