Sorry to hear that. Could you please explain more about what difficulties you're facing while adding a document? which version of InDesign you're using? What is the version of InDesign in which the document was created that you're trying to add. What operating system you're on?
I am using CS 6. My document is saved on my computer but I can not find it
on IN Design.
If you're using windows machine then search for the file using this wildcard *.indd if you forgot the filename. If you're using mac then in the spotlight search for *.indd and look for your file in the results.