Small Blue Pill E 64 What's This Pill I Found?

What's this pill i found? - small blue pill e 64

I can not find this pill at the end of my drawer, and I do not know what it is.
It is blue, small, round and has the capital and expanded with the number 64 below. Does anyone know this?
and please no comments about pills that I have found no intention to consider simply want to know what it is. Thanks