Detect DotNet is a free program which lets your identify the version of .net framework installed on your computer, it will work even if there are multiple versions of .net framework installed on your computer and you will get to know all the versions of .net frameworks on your machine.
This small utility has no user interface, it has a small program exe which when you double click will show all those versions of .net you have installed and also those versions which are not installed on your computer.