firstly it was only 35 mb Free .i was unable to install new app..then i deleted tombstone and log in data and got some space...further i found a folder that i do not understand....it is data/core....i Google it but couldn't found anything understandable.... i am using micromax a116 rooted...please do reply. thanks
I can't quite understand what your asking, but it sounds like you are running out of space, is that right?
If you are having issues with strange files that you don't know what they are taking up lots of space, I would recommend using TitaniumBackup to backup all your applications with data, then do a data factory reset, then VERY SELECTIVELY restore applications with data, ONLY restore the application data that you are 100% sure about, like games you're playing, contacts storage, SMS storage, things like that. Don't be afraid to restore apps 1 at a time checking each time that you aren't getting a rediculous amount of space being taken up.
Sometimes when things get messy a factory reset is the best thing you can do.
Hope this helps.