Q: Keychain

Hi,

I can access the "keychain" although I have tried some dozen of passwords.

Actually, my iMac (2,5 GHz Intel Core i5 - 4 GB 1333 MHz DDR3 - OS X El Capitan, Version 10.11.4) has started with asking for the password of the keychain.

I can't remember when I purchased this iMac in 2012 whether I have put any password for this keychain.

HOW can I re-boot this keychain?

Thanks for any help!

Regards, Ronaldo (indiagaucho)