How to recover data

hi
i am a newbie to this whole 3d world . i have jaust started learning blender.
After wasting few hours/days i can build only one object/ character. But accidently i delete the whole data. this is happening frequently. If i am in edit mode i can recover the changes the thru mesh > undo editing . But if i am in object mode i donno what to do , how to recover. Can any body tell me how to recover these kinda accindental loss?
thanx in advance

Use backuping. Blender has autosave function. You can find it in the settings http://en.wikibooks.org/wiki/Blender_3D:_Noob_to_Pro/Blender_Windowing_System#User_Preferences
. Check out the Auto Save and you can decide how many backups Blender makes and at which interval it makes them.

These backup files are saved as yourWork.blend1, yourWork.blend2, yourWorkblendPutNumberHere …

You can open them normally as any other .blend file.

you know… blender has global undo now

in object mode even… control+z is the shortcut