Windows Vista - How get back "open with..."

Whilst trying to open a .exe file this morning my computer came up with a message saying it didn't know what programme to open the file in. I was in a rush and assumed it would pick the best choice from a search so pressed ok without looking at the options. It then proceeded to change all of my .exe files to be opened with adobe acrobat. Therefore nothing will open straight from being clicked on. The files were then changed to be opened by "Windows Explorer" and none of the files will open. And now the open with button has gone completely.

Does anyone know how to solve my problem ?

 

right click file, down at the middle of the menu is the open with feature, then you can choose a program to open it with, or set the default program to open it with.