I use gmail for sending emails. I was using my personal email id for receiving and sending the matter for my office, but I got transferred from there now. The email was created by me, and my own mobile number was given. (Which other mobile contact can I use otherwise?) It was made from my personal computer. Now after transfer I used to check my emails and use it occasionally. But a few days back I got an email at my other email id that the password of that email id has been changed by someone. I immediately checked it and was shocked to see it changed. I then tried to revive it, and the gmail asked me to fill my mobile number at which I wrote my mobile number and a number was sent at my mobile which I filled and got the password changed again. Now, again I have to disclose my password to my former office. They changed it again. I tried to revive it, but I was told that 'too many dattempts' are made. Then I contacted my source in the office and he disclosed me the new password, but I fear they will change it again.

What should I do now to be able to again access or able to change the password in future, if they change it again and my source fails to help me intentionally or unintentiionally. Someone told me that after some time, that option will again appear and I will be able to revive it again. (Then I will sure not disclose it to anyone). Please tell me what to do?

If this is your personal gmail account I don't see why your office should have to know the password for it. Just let everyone that sends you emails related to your former work know the address of the new contact person (and cc the new contact person). Since you know the password now, change it and don't give it to anyone.