Anybody know how to activate Biab , it asks for serial number and I don't know it chat seems to be offline today ?

If you have a hard drive, it is likely on there somewhere, otherwise in an email or in your account on the main site.
Chat appears online here, though haven't actually tested it, but it says OPEN - CHAT NOW at the top of this window
Even if you have to send an email via chat, they are usually petty responsive

Thanks rharv sorted !

Video tutorial:

https://youtu.be/8mbJleZ0QGs

According to the tutorial:

If you have an online installation, procedure given.

If you have an offline installation, procedure given,
but involves talking to a human (which means Monday for you).

(Mine are offline, so I've talked to a human. Very nice and very fast.)

(If your BiaB is many years old, you'll have to use the offline procedure.)

P.S. You can create an account (email, password) within support (NOT the same as the forums). There you can find all your products, serial #'s etc.

P.P.S. Also, if BiaB is installed, you should be able to click on the "Help" tab at the top, and then click "About Band-in-a-Box" to get the page that shows your serial #.