mail hacked

i have big problem
my gmail was hacked and i dont know how!!!

just give a person my mail name and after while i saw that my password was changed and stole all mail content

i want to know
How that hacker do that??and how can i get it back??

plz help me guys

cheers

Have you tryed password recovery? if it was hacked then they would have changed your secret question thing. Does the person know you personaly? or did you have some dumb password which relates to user names or something that can be spoted? for example was your password messi_19 or the name of the football team in your advatar barca fan ?i don't know how to hack but this is what i would do first if i was going to atempt it.

Best thing i could think of is contact gmail provide them with your ip details before previous passwords when it was opened secret question amongst other things and you may get it returned to you.

If it has no personal information linked to you meaning real life stuff such as bank and shop details i would not worry about it just change all your passwords everywhere else that is related to that emaill account.

Phishing ?
Keyloger?