password

I could not install Mackeeper since I have no password , pls advise

My advice to you is not to install MacKeeper in the first place. It's a load of rubbish, will do no good and may do harm, and is quite difficult to remove. You do not need it: your Mac is quite capable of looking after itself.

As to the password, you are presumably being asked for your admin password for your user account on your Mac: only you know that. No-one else can retrieve if for you (nor would you want them to).