Nigerians nor go kill me with their sense of humour,see what I sawߘ0ߘ

SOLVE THIS RIDDLE:
I am an object,

In my military regime, I ruled for only 20 months (31st Dec 1983 - 28th August 1985) and was overthrown.

Now, in my civilian regime, I ruled for exactly another 20 months (29th May 2015 - 19th January 2017) and went for indefinite holidays.

Today is exactly 20 days since I left office to unknown destination.

Who am I?