What to do if your Google account gets hacked

What to do if your Google/gmail account is hacked?It will be a nightmare for you if your google account gets hacked,Most of the people in these cases waste their money contacting the password recovery services wasting their money,I dont say they dont get back password,But you can do it by putting in some effortsI will begin with Google. it's a pity thing your account got hacked. in most cases it