I can't access my G4, I do not have the password or format disk

I have received this Mac from a friend who re-formatted it before giving it to me. I was initially able to use it until recently. 1st, the last row of the keyboard no longer functioned, so I turned it off. 2nd, when I turned it back on, it displayed a start up screen that asked for a username (which already had "Macintosh Macintosh") and a password. I did not know the password & neither did my friend. I think he may not have the original start up disk (but I will ask). Is there any way to bypass this? Is there a general password or will I need to acquire the start up disk (or purchase a new one in the event my friend may not have it)?



Thanks in advance