>Then I asked him to go to the C:\Windows\Microsoft.net\Framework\v2.0.50727\Temporary ASP.NET file and delete folder MyApplicationName. Nothing helps. I cannot reset the IIS because there is another important ASP.NET app running on the server.
>
>What can we do to UnDo the precompiling?
>
>Thank you in advance for any suggestions.

You can't really "undo" it, but you should be able to drop a full set of files (ASPX, .DLL, etc.) in the same folder - I would make sure the files in the bin and App_Code folder have also been removed, then force the site to reload. Since IISRESET isn't an option, if the website is running inside of it's own application pool you can recycle it which should force everything to be reset. (Go into IIS Manager, select the server, Application Pools, then the app pool for your app. Right-click and select Recycle. Editing the web.config file should also force things to unload/reload.