till yesterday , my tc 3.0 was working fine but now when i try to open my tc , it cant with the following window appearing C:\DOCUME~1\COMPUTER\Desktop\TURBOC~1.PIF Invalid program file name, please check your pif file.Choose 'Close' to terminate the application how to make my turbo c work again

Your shortcut is corrupt. Try creating a new shortcut to the program (Whereever that is), and checking that the program it points to acutally exists. As for what caused it, it could be any number of things such as a dying hard drive or virus / spyware.