Δαφνη Ευτυχια Αρθουρος

What kind of sparcstation do you have (it doesn't make a difference, I'm just curious)? What OS is it running? Generally speaking, the way to do it is to boot into "single user mode". To do so, issue the command "boot -s" from the ROM prompt. Sometimes that will drop you into a root shell without prompting you for a password. If so, just edit /etc/passwd, and remove the password field for root. Then you can use the passwd command to set it to what you want. If it still prompts you for a password, then the procedure depends on what OS you have (but could be as simple as reinstalling if there's nothing on the machine you need).