I have installed Eclipse Luna(4.4) on my system using the binary file and it is having the MPC plugin which is downloaded from the site :
http://download.eclipse.org/mpc/luna/
Still i am unable to find the Market Place in the Help tab, but in the
About Eclipse >> Installation Details >> Installed Software' , 'Marketplace Client' is visible.
Please help me how to Launch it.
Edit- Attaching the screenshot from Eclipse which shows the MarketPlace is installed, still it is not showing in Help Menu
Go to Help/Install new software from the menu, select the Juno update site (http://download.eclipse.org/releases/juno 'try this repository'), and look for the Marketplace client it is in the General Purpose Tools category
Either drag-and-drop the install URL from the Marketplace website to your Eclipse instance (the main toolbar is a good drop target), or open Help/Eclipse Marketplace... to start it. See also the Marketplace documentation.
->open (your eclipse luna folder)-->configuration-->config ->open the config file with wordpad and add the below lines at the end.
org.eclipse.ecf.provider.filetransfer.excludeContributors=org.eclipse.ecf.provider.filetransfer.httpclient4
->save the config file ->Now restart the eclipse luna and try to access the market place.
Did you try update your Eclipse installation?
I had the same problem and I solved it selecting all updates from:
Help -> Check for Updates
I hope this helps.
来源：https://stackoverflow.com/questions/24772674/market-place-not-working-in-eclipse-luna