The problem is the character flies in opposite direction when i play the file.Can anybody rectify the mistake and suggest necessary correction.

Have no clue to what you are asking!

when i tried uploading the blend file the forum replied that it had incorrect extension.

Quote - when i tried uploading the blend file the forum replied that it had incorrect extension.

You'll almost certainly need to link to a location offsite, because while you can change the extension to something the forum software allows (e.g. .txt or .doc) unless the file is less than 200KB it still won't attach to a post.

Post your blend file, for free, at...

http://www.pasteall.org/

Post link back here...

Still not sure what you are asking!

I have pasted it here http://www.pasteall.org/blend/1428  . The problem is the moment i play the file the princess flies in opposite direction to the natural direction of gravity.

Sorry...I do not know anything about the game engine in blender.
Noobe here...but started about 5 months ago. Opening your file was first time in the game area, lol.

If you do not get any help here, I would look over at blenderartist.org site...in the "Game" section.
Should be able to get help there.

If the game engine is same as physics engine then a gravity value is positive in the positive z direction, so you need a -value to define gravity going down?

basically the problem is not with gravity,while other objects r falling downwards,the princess is falling upwards,is there a gravity setting for each object.also the princess was taken from a diff file

Quote - basically the problem is not with gravity,while other objects r falling downwards,the princess is falling upwards,is there a gravity setting for each object.also the princess was taken from a diff file

  You've set the armature to a rigid body.  I don't think that's what's normally done, I've never done that.  What I've seen before is parenting an armature to a Plane and defining the plane as a rigid body.  Attach your movement keys to the plane.  Make the plane invisible. 

  I think the armature should only be used to define the deformation of your mesh, not the physics of it. 

  I tried attaching your armature to a plane, turning off the rigid body on the armature and turning on the rigid body on the plane things seem to work correctly.