Ok folks.. long story short, I was developing on a computer that I no longer have access to. I was able to retrieve the source code, but not the .keystore file used to sign
I have generated the signed apk using android studio , so in the "key Store Path" i just typed some name without extension, and fill this popup and signed the application.
next time for publishing the application i don't remember the path and name where it was created.
somehow i find the default location which is "C:\Program Files\Java\jdk1.8.0_45\jre\bin" : \jre\bin
and in that folder short by date ,then i tried with recent file and it worked for me.
Note : you should remember the Key store password and key password.