If someone takes over your online account, accesses your data or the hardware/software on your computer without your permission, that person is guilty of the offence of unauthorized access(( Section 43(a), The Information Technology Act)). For example, if someone gains access to your Gmail account without your permission.
The offender is liable to pay you damages/compensation by way of a monetary amount not exceeding one crore rupees. However, it needs to be established that the offender accessed your account dishonestly.(( Section 24 and 25, The Indian Penal Code, 1860.))