I forgot my password when you enter the password three times, give me this number is 00512 Acer Extensa 5620z
I don't know, but send a mail to acer support, they'll know what to do. But does it also block the boot? Cause otherwise you can try to flash it, which will in most cases also reset the cmos settings.
Flashing a BIOS for no reason other than to clear the CMOS/password is too risky. Better to just take the battery out for a minute...(the CMOS battery, not the rechargeable one...)
But then he must be willing to open his laptop, I consider that to be more dangerous than flashing the BIOS.
Point taken, but usually the battery is hidden underneath a cover that's not hard to take off...flashing the BIOS carries a risk of bricking the whole machine.