Tips to find if Your Gmail account is Hacked

• Login Your Gmail Account  
• At the bottom of your Gmail inbox there is a ‘Last Account Activity’ section. Click on ‘details’ to launch the full blown monitor.

See your Gmail Account recently

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So,as you can see in the image there is a red bar showing my account access from turkey which means that someone tried to access my account or he may have possibly done so.So whenever you see this,immediately 

change your password.

Sign out All Other Sessions – If you forgot to sign out on a public computer