Did you check your iMac's sharing settings through System Preferences? Restarted your iMac?
Your system profile is a complete blank!
When posting in Apple Communties/Forums/Message Boards.......It would help us to know which iMac model you have, which OS & version you're using, how much RAM, etc. You can have this info displayed on the bottom of every post by completing your system profile and filling in the information asked for.
This will help in providing you with the proper and/or correct solutions.