Solution

If you are using Windows environment, mostly when you save .txt files in other extensions, it will not save proper name as you've given.
For example: If you want to create test.ctl , behind the scene Windows will save it like test.ctl.038739 283 which is not proper controlfile.

Solution:
Open the file
Save as "test.ctl" (put the name within "" in File name bar and save...